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ax-15 or nv3550??

jmeti000

NAXJA Forum User
Location
san antonio,tx
im trying to decide on which to swap cuz my ba10 is going out on me. i found an ax-15 from a 96 in the local yard i can pick up for about 120, but i was wondering if there would be any huge benefit to having the nv3550 or if they are relatively equal when compared. i dont do any major crawling...more like your weekend warrior on occasion and mainly a DD. oh, and i plan on keepin my np231 and just changing out the input since it works like a charm.
 
-3350 is a stronger transmission, but the AX-15 is pretty good itself. Behind a relatively stock engine, the AX-15 is fine. Also, the -15 is a lot cheaper. The 1st gear ratios are about the same(4-1) in both transmissions, so the decision doesn't affect your crawl ratio.
 
The 3550 is rather more difficult to find in XJ trim (2000 maybe, 2001 definitely,) and getting one from a TJ would involve either finding/buying an XJ transfer case adapter housing, or "massaging" your transmission tunnel (the TJ has the transfer case clocked a little flatter for more ground clearance.)

Good news? You've got a 1996 AX-15, which is external. Your options open up a bit more, since you don't need a bellhousing for the -3550, and that's a common reason to get rid of a transmission. The bellhousing and clutch fork from the external AX-15 (1994-up XJ) will fit the -3550 directly!

I believe the -3550 was also used in some of the later Dakotas with transfer case clocking similar to the XJ, so that also gives you some options (you can't use the Dak bellhousing with the XJ, since it's probably a Chrysler LA-block bolt pattern. So, get the -3550 from the Dak, overhaul it, and move the AX-15 bell over when you swap gearboxes. Problem solved.)
 
The AX-15 is still in production. New units and parts are readily available. The NV3550 is out of production. You cannot buy any new parts for it (maybe NOS if you can find it). Call a few places and verify this.

NV3550 is a noisy transmission. Many, many new Jeep owners took them back to the dealer - under warranty - because of the noise. They were told this is normal operation, tranny not defective.

I am on my second AX-15. Was going to install an NV-3550, until I started researching it. If you want to upgrade, then install the AX-15 terminater, but not the NV-3550.

Research the issue. You will find the NV-3550 is not an upgrade to an AX-15. Start your research by reading this http://www.jeepsunlimited.com/forums/showthread.php?t=896905
 
You will find the NV-3550 is not an upgrade to an AX-15. Start your research by reading this http://www.jeepsunlimited.com/forums/showthread.php?t=896905
True, the -3550 was a last-year addition to the XJ, the same way the low pinion "TJ" front axle was. Jeep used them because they were already putting them in the TJ, and didn't feel like paying for the small quantity of "XJ specific" parts. It was a cost saving measure.

The AX-15 is still in production. New units and parts are readily available. The NV3550 is out of production. You cannot buy any new parts for it (maybe NOS if you can find it). Call a few places and verify this.
While maybe not in production, the -3550 was simply a NV-3500 with a removable bell housing. All internal parts are the same(I talked to one of their engineers about this) Parts will be available for a long time to come.
 
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