what size tires are those?
Before I did a 3.07 swap I'd go get a pair of later model 3.55 geared axles. Give the D44 to your pops, put stock 8.25/d30 in it.
30" tires and 3.55s is stock revs per mile.
3.73s and 31's is stock revs per mile.
I've done both.
The other thing is that 3.07 gears axles are harder to find when you need to yard a replacement. 3.55 gears one are everywhere. That's why my MJ is getting 30's and 3.55's. Easy to find axle replacements, cheap tires, factory gearing so the speedo is correct. Plus, 30's look right on a stock MJ.
Also, going from a 44 to a 35 will make you find a new rear shaft, or have yours lengthened. I assume you've got the stock case in there that has the slip yoke into the case. It's easier to come by the late model fixed style shafts these days since most of the early stuff has died.
edit:
deeper gears in the axle will relieve some stress on your BA10 as well.
I have the correct rear shaft. I really would like to keep the 3.55 ratio. It's on 33s. The Jeep came with a HP D30 from a 94 XJ that has 3.55s, heres the backstory.
My dad had a 94 XJ. 8.25/D30, 3.55s
He bought a TJ D44 front and XJ D44 rear. He had 4.56, ARBs, chromolys, new bearings, and a new carrier installed from the a guy who knows a guy who owns a shop that knows a guy that knows how to do it.
He gave me his D30 and I swapped out the vacuum front axle.
I found an XJ D44 on craigslist, with 3.55s.
Then I sold my vacuum D30, but we kept my dad's 8.25
The front end of my dad's Jeep started making wild howling, and the 4x4 shop said it was installed wrong. Mind you this is probably 2 years later.
My dad was tired of working on it and bought a 98 TJ. The front axle works, but the rear axle would require grinding off the leaf spring perches and welding on all of the TJ brackets on the rear axle. We looked and the cheapest kit we could find was 350 bucks, plus the front end needed new bearings, and it costs 200 to have the 4x4 shop reshim the carrier, which my dad decided he didn't have the time or money to do it.
He sold me the front axle, and the internals of the rear axle, and sold the D44 separate. He bought an HP30 from Craigslist, put back in the 8.25, put stock suspension on it, I swapped his SYE tail shaft on mine, then he sold it.
I got the axles for a screaming deal. I paid for the new front bearings, to have the front carrier reshimmed, and I paid the 350 to have the ARB installed in my XJ D44. Then I did a manual swap, SOA, long arm, etc.
Here's where the 87 comes in.
A friend at work bought this Jeep. He told me it had wrong ratios. I crawled under it to see the rear diff is 3.55, front diff is 3.07. I told him most likely, someone swapped in the rear diff and didn't pay attention to the ratios. So I sold him the 3.55 front diff that was originally in my dad's 94 XJ, then under my MJ. He didn't get around to ever installing it. Then he sold the Jeep to me.
So here's what I got, 87 XJ, 3.07 vacuum disconnect D30 (installed), D44 3.55 (installed) and the 3.55 non vacuum D30, (uninstalled). I also have a 3.07 D35 from a wrecked 1990 XJ. So here's the plan:
Install the 3.07 D35 in the 87, and my dad is going to put the TJ perches on the XJ D44. Then he will swap that in with the HP30 and will have 3.55s in his TJ. Right now he's on 3.07/33s.
We only bought this because my dad wanted the D44. At this point, a friend of mine really wants to buy it. Once we swap the axle, get it running right, and fix a few safety issues, we will probably sell it to him.
Sorry this is lengthly, but that's the story haha
