• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

XJ - 5.0L swap.

Damn. 20% at PNP this week. That's a $150 motor.
I've even got a spare (wrecked) XJ (buddies write off) sitting in the driveway just waiting for fitment, and it's even got a complete motor I can use for core.
I think this may have to happen this week.
 
Wait, is there a driveline that I could just swap in complete from motor to t-case, into the XJ? Chev is all drivers drop right? I've seen hints of other guys just dropping the whole lot in and not worrying about adapting bellhousings/tcases... Is this a simpler route?

I think chevys are all passenger side drop. Frankz used a hybrid 241 t/c if I remember correctly. Using some sort of hybrid transfer case makes sense. I bought the adapter to connect to my np242 to the 4l65 but either way you will need to do something. I would definitely suggest using the v8 transmission (from whatever you end up getting) rather than trying to adapt either an aw4 or ax-15.

1. From what I understand, the lower profile LS intake can be bolted on, but there are some issues with bracketry. Who knows what needs to be done to get the LS intake installed, and will it negatively impact performance/economy?

You either need a new water pump and spacers, a new water pump and all new accessory brackets w/accessories, or if you have a cable throttle body you might be lucky enough to just mess with the water pump outlet a bit. On that note, what you would want is the LS6 intake. The LS1 intake is the worst flowing GenIII intake and will net you power loss all the way across the power band. With the LS6 you would need to reprogram for the higher flowing LS6 injectors or make a rail adapter to run the truck injectors. You also still need to modify the alternator bracket to bring it down far enough to clear the hood.

2. Is there any way to get an AC pump mated to the LM, and still under the hood? (OBA pump)

Yes. I have my stock 1996 XJ compressor under the hood. It just takes pretty basic and easy to make custom brackets (it lines up pretty close just straight off the water pump bracket bolt holes for some other accessory bracket that I didnt use)

3. Fuel delivery... I'm not sure which Jeep I'd be doing the swap in. Either a 98 or an 88. What fuel delivery options do I have for either? Can the 98 in tank pump be modified to push the regulated 60psi, or does it make more sense to just modify the pump for no pressure regulation, and regulate at the rail and install a return line? Or should I do like FrankZ and just drop in a chevy pump into the XJ tank?

You can run the engine of the stock pump and 50 PSI for the 98 (returnless in 98 right?), though it wont be capable of supporting the full power of the engine. The 88 is return style right? If you you might not need to do anything since the pump is probably capable of supporting the flow needed. For the 98, my suggestion would be to replace the pump and run an external regulator and return.

4. FrankZ talked about putting the chevy cluster into the dash but I don't think it ever got finished. Anyone know more on this?

I dont suggest that, nobody seems to be successful at it. Im running my stock 1996 dash with all gauges (its a gauge cluster not idiot light style) working except tach which I just havent got around to. The 98 cluster would be the same if its gauge style like mine (pretty easy) or you would need to put all new gauges in if its idiot light style since there obviously arent gauges. The 88 would be easy for all the gauges except you would need an adapter for the speedo since the trans has electronic speed reading and an 88 is cable style I believe.

6. 4L65E or AX15? I prefer manual, but that's probably just because I'm used to having a wimpy motor. I've never driven an auto that was mated to a power plant making more than 150hp :p.

4l65e. Definitely not AX-15. If youre wanting manual, do an nv4500.

7. I've heard the water pump needs to be spaced out.... is that only with the LS intake?

Just for LS. Truck accessories are spaced out about 1.5" further than corvette accessories. F body (camaro, firebird) are spaced out 0.75" more than corvette accessories.

6. What 5.3L's are going to be the easiest swap?

They are basically all the same. Some are better than others (the L33 is the best gen III 5.3 since it has aluminum block and flat top pistons for higher compression). For ease the only real difference is going to be stuff like does it have an EGR (most 2002+ dont) and does it have electronic throttle body (most 2003+ do). Personally having owned a few cars with electronic throttle body I wasnt afraid of that so I got an 04 engine. The E-throttle body makes the swap a tiny bit easier I think and in my opinion EGR is to be avoided like the plague.
 
Last edited:
I think chevys are all passenger side drop. Frankz used a hybrid 241 t/c if I remember correctly. Using some sort of hybrid transfer case makes sense. I bought the adapter to connect to my np242 to the 4l65 but either way you will need to do something. I would definitely suggest using the v8 transmission (from whatever you end up getting) rather than trying to adapt either an aw4 or ax-15.

LOTS of chevy are drivers drop. I know for a fact that any 97 trucks are drivers drop as I just did a SAS on my roomies K1500. I'm pretty sure all Chevy, 92+ were driver drop. The caveat was that all their DD were on IFS. I don't believe Chev ever made a solid axle drivers drop.

As for transmission, I really prefer manual, and everyone says the AX15 will easily hold up to around 325hp without any complaints. That said though, the bellhousing adapter will cost around $350, or I could instead just stick with the 4L60x which saves me a bit of money and is probably a better idea for the type of wheeling I do. The big question for me is, are there any T-cases that either came with, or bolt directly to the 4L60x, that are drivers drop? I'd expect there must be, as my roomies SAS we just finished was DD and we used his stock T-case (though he's got a manual trans).
I'm just trying to figure out why so few people retain the entire GM drivetrain from engine to t-case. I figure there must be a reason but I've never heard it voiced.

I'm pretty sure my roomies T-case is an NP241 as well, which from what I understand bolts right up to the 4L60/65E.


What'd you end up swapping in for a motor? I'm trying to find someone who's brain I can pick real quick.
 
LOTS of chevy are drivers drop. I know for a fact that any 97 trucks are drivers drop as I just did a SAS on my roomies K1500. I'm pretty sure all Chevy, 92+ were driver drop. The caveat was that all their DD were on IFS. I don't believe Chev ever made a solid axle drivers drop.

Yeah I was just considering solid axles. I guess it doesnt really matter for the T/C though? Are IFS t cases clocked funny?

As for transmission, I really prefer manual, and everyone says the AX15 will easily hold up to around 325hp without any complaints. That said though, the bellhousing adapter will cost around $350, or I could instead just stick with the 4L60x which saves me a bit of money and is probably a better idea for the type of wheeling I do. The big question for me is, are there any T-cases that either came with, or bolt directly to the 4L60x, that are drivers drop? I'd expect there must be, as my roomies SAS we just finished was DD and we used his stock T-case (though he's got a manual trans).

Torque kills transmissions, not so much horsepower. I wouldnt put an AX-15 behind a 5.3. Im sure it would survive for a while or possibly even forever, but doesnt seem worth the risk to me. If an IFS transfer case works, which I dont see why not unless it has a funky clocking to it, just about every automatic produced by GM for light duty (colorado, s-10, yukon, silverado 1/2 ton, was a 4l60 variant and any 4l60 variant after about 1996 (?) had the same bolt pattern on the tailshaft housing so any of those transfer cases should work. Most people I think dont use them because they tend to be very long and lots of them are vacuum controlled.

What'd you end up swapping in for a motor? I'm trying to find someone who's brain I can pick real quick.

Mine is a 5.3 from a 2005 yukon, with a silverado SS 4l65e, and NP242 adapter. I havent bothered to check what the actual engine code is but from what I gather its probably an LM7
 
Yeah I was just considering solid axles. I guess it doesnt really matter for the T/C though? Are IFS t cases clocked funny?



Torque kills transmissions, not so much horsepower. I wouldnt put an AX-15 behind a 5.3. Im sure it would survive for a while or possibly even forever, but doesnt seem worth the risk to me. If an IFS transfer case works, which I dont see why not unless it has a funky clocking to it, just about every automatic produced by GM for light duty (colorado, s-10, yukon, silverado 1/2 ton, was a 4l60 variant and any 4l60 variant after about 1996 (?) had the same bolt pattern on the tailshaft housing so any of those transfer cases should work. Most people I think dont use them because they tend to be very long and lots of them are vacuum controlled.



Mine is a 5.3 from a 2005 yukon, with a silverado SS 4l65e, and NP242 adapter. I havent bothered to check what the actual engine code is but from what I gather its probably an LM7

I'll have to hop under the roomies truck tonight when he's back to take a look but I don't think it was clocked weird at all. Actually, his buddy also has a k2500 with the 4L65e and stock T-case, so that'd probably be a better example.
I do know that my roomies K1500 t-case is mechanically controlled, so regardless of what I find bolted to the 4L6xx, there IS a t-case that should work. I know the yolks are a stupid size but I found conversion yolks for $80 a piece. Seems like a better idea to retain the entire driveline to the t-case, and just swap out the yolks, but still wondering why more guys don't do it....
Is the 4L6XX any longer than the AX15?

Also, is your 5.3 in an XJ? If so, what'd you end up using for headers and intake?
 
I'll have to hop under the roomies truck tonight when he's back to take a look but I don't think it was clocked weird at all. Actually, his buddy also has a k2500 with the 4L65e and stock T-case, so that'd probably be a better example.
I do know that my roomies K1500 t-case is mechanically controlled, so regardless of what I find bolted to the 4L6xx, there IS a t-case that should work. I know the yolks are a stupid size but I found conversion yolks for $80 a piece. Seems like a better idea to retain the entire driveline to the t-case, and just swap out the yolks, but still wondering why more guys don't do it....

Yeah the t/c in my dads 2500 is manual also (although its on an allison trans). Most of them are vacuum in that type of vehicle and I have no idea what the differences are or if the same t/c is available both ways.

Is the 4L6XX any longer than the AX15?

They are similar. The overall length of a 5.3 with 4l60, transfer case adapter, and transfer case is a couple inches shorter than stock 4.0/aw4/np242

Also, is your 5.3 in an XJ? If so, what'd you end up using for headers and intake?

Yes mine is in an XJ. Intake is a modified spectre intake but you could use any combination of 4" elbows, and fittings. In CA you need a CARB sticker even on an engine swap so I had to have the spectre that was stickered for the 5.3 trucks. The manifolds are modified LS3 camaro manifolds, another product of the CA smog system. I would have used Novak headers if I could still pass smog visual inspection with them.
 
Yeah the t/c in my dads 2500 is manual also (although its on an allison trans). Most of them are vacuum in that type of vehicle and I have no idea what the differences are or if the same t/c is available both ways.



They are similar. The overall length of a 5.3 with 4l60, transfer case adapter, and transfer case is a couple inches shorter than stock 4.0/aw4/np242



Yes mine is in an XJ. Intake is a modified spectre intake but you could use any combination of 4" elbows, and fittings. In CA you need a CARB sticker even on an engine swap so I had to have the spectre that was stickered for the 5.3 trucks. The manifolds are modified LS3 camaro manifolds, another product of the CA smog system. I would have used Novak headers if I could still pass smog visual inspection with them.

I meant which intake manifold are you running, and how'd you get the accessories under the hood? Running the stock truck manifold, or did you switch to the LS style intake man? Did you have to modify water pump or accessory brackets?

I'm coming up short on info for the newer chev trucks. Everything has the 4L6xx but seems they all have different t-cases. I figure as long as I can track down a 6 bolt, driver drop NP241, I should be set. Most of the newer t-cases don't have a removable tail cone, which I'd probably need for the SYE. I may end up retaining either the NP231, or both the 231 and the AX15, but it really depends on what I find will bolt on to the 4L6xx. I'm almost tempted to just go manual, with the NVwhatever that came in the mid-late 90's k1500 (my roomies truck again)... Though that said, he has a TONNE of issues with his clutch conking out every time his truck sees water.
 
I meant which intake manifold are you running, and how'd you get the accessories under the hood? Running the stock truck manifold, or did you switch to the LS style intake man? Did you have to modify water pump or accessory brackets?

LS6 intake w/LS6 injectors, f-body pump with 3/4" spacers, modified alternator bracket to fit the alternator under the hood but thats it all other accessories fit properly if you use a spaced water pump and they also fit under the hood. I had to build the a/c brackets from scratch of course since the XJ compressor is pretty different from the truck one.
 
LS6 intake w/LS6 injectors, f-body pump with 3/4" spacers, modified alternator bracket to fit the alternator under the hood but thats it all other accessories fit properly if you use a spaced water pump and they also fit under the hood. I had to build the a/c brackets from scratch of course since the XJ compressor is pretty different from the truck one.

Know anything about trans/t-case options? I know most guys go 4L60-E and Jeep np231, but I can't figure out why no one just retains the chevy np241 that's commonly bolted to the back of the 4L60-E? I know it's a bit longer this way, but assuming I'm moving my rear axle back another 6" anyway, I don't think this'd be an issue.
Any other trans/t-case combos that I might consider?
 
Know anything about trans/t-case options? I know most guys go 4L60-E and Jeep np231, but I can't figure out why no one just retains the chevy np241 that's commonly bolted to the back of the 4L60-E? I know it's a bit longer this way, but assuming I'm moving my rear axle back another 6" anyway, I don't think this'd be an issue.
Any other trans/t-case combos that I might consider?

Also, I'd still prefer to go manual now that I think about it. I don't like the idea of being 200km out in the bush and have my transmission conk out. Not much to go wrong with manual that will make it impossible to get home.
 
Also, I'd still prefer to go manual now that I think about it. I don't like the idea of being 200km out in the bush and have my transmission conk out. Not much to go wrong with manual that will make it impossible to get home.

I've seen more manuals spill their insides all over the place than I have auto's.
 
Know anything about trans/t-case options? I know most guys go 4L60-E and Jeep np231, but I can't figure out why no one just retains the chevy np241 that's commonly bolted to the back of the 4L60-E? I know it's a bit longer this way, but assuming I'm moving my rear axle back another 6" anyway, I don't think this'd be an issue.
Any other trans/t-case combos that I might consider?

I honestly dont know. The person to talk to might be Frankz on that. I would suspect the reason is a combination of different issues. The t/c is pretty long, the t/c is not all that much stronger to be worth the length, and a lot of people who are doing swaps like this have very built rigs running double cases or aftermarket cases.

I've seen more manuals spill their insides all over the place than I have auto's.

I would agree with that. In addition, the 4l60 is a pretty smart transmission and most of its failure modes will still allow you to limp off the trail while trying not to aggravate the failure (skipping gears, no t/c lockup, full line pressure, etc. it has a number of ways that it works to not make things worse depending on what the issue is). Since there isnt much to fail on a manual, most failures result in you not going anywhere.
 
Back
Top