Okay, I think I've dug through about all of the internet that I can handle looking for this - most folks are dealing with the '92-'96 Dakotas when doing manual transmission swaps.

I have a '90 4WD with the NP2500 (NV2500, A535... pick a name). The truck has over 300K miles on it with one transmission rebuild to my knowledge. I'd like to at least be prepared in case it goes out again.

My question: Does anyone know if an AX-15 or NV3500 from a later 4x4 Dakota (at least, up through '96) will drop right in to the older "pre-V8" trucks?

The parts books shows the same front drive shaft for at least all '90-'96 with a manual transmission, so I shouldn't have to replace that. I also think that means the transfer case is located in about the same position front-to-back in the truck, so my rear drive shaft should work, too. I'd buy a new clutch assembly so that can also be ruled out.

I think I just need to know if the transfer case bolt pattern. It looks like my NP2500 uses a bolt-in extension while the AX-15 and NV3500 have that as an integral part of the transmission. Anybody able to vouch that everything checks out? Is there something I'm not thinking of? It'd be great to get this info out here for others to reference as well.

 

Either will work, but the NV3500 is a heavier transmission and the bell-housing is integral to the trans itself, that is, it doesn't separate. That makes getting it into place significantly harder. It's also roughly 5/8's of an inch shorter, which brings the t-case slightly forward with the resulting effects on the drive shafts. Also, if you do the NV3500, get one from a Dakota, as the Ram version has the shifter in a different location. I know all this from having put a NV3500 in an '89 Dakota that previously had the NP2500.

The AX-15 is probably a better choice in your case. It's stronger than the NP2500, and it will bolt right up at the engine and the t-case. Because the bell-housing can separate, you can put the clutch and bell-housing on first, then bolt up the gearbox. As far as the t-case bolt pattern, all three trans here use the same NP231 t-case in 4WD Dakotas.

What I can't tell is the length of the AX-15 in comparison to the NP2500. It's probably very close if not the same, I just can't say for sure. Someone on the forum should be able to take a measurement for you though.

 

I can measure my Ax-15 tomorrow and post up.

I don't know anything about this swap, but that's awesome that you're at 300,000+ miles!!! These really are good trucks...I think they are above Chrysler's average vehicle and definitely don't deserve the bad rep that Dodge vehicles get.

 

Awesome! That's exactly the kind of info I was looking for.

Interesting info about the NV3500 being slightly shorter. I guess it's not enough to need a different front driveshaft since it just collapses a bit more, but maybe the rear does need to be a bit longer. There were so many different rear drive shafts listed in the parts book that I had a hard time keeping everything straight. Some of them are probably the same length but with different components, but you can't tell from the part number listing. They even changed year-to-year for the same application in a few cases. I did know about the Ram-Dakota NV3500 difference thanks to several previous posts on this forum.

I'm glad to see a vote for the AX-15. That's the transmission I would likely go with - they're more common and are plenty stout for my TBI 3.9's 195 lb-ft of torque. It's just nice to know that a Dakota NV3500 will work (maybe with a rear drive shaft swap if required) in case a good deal pops up.

The NV3500 has a little better overdrive which would be nice for unloaded highway driving, but that's not enough to sway me. I really like the gearing of the NP2500 with 3.55s and the AX-15 is very similar.

I bought it last summer with 304K and I've only put a couple of thousand miles on it since then (most of that was a 1200 mile round-trip). I agree that they're solid trucks. The NP2500 seems to be a bit of a weak link but I still think it holds up better than most automatic transmissions of the era.

My current main gripe - which is pretty minor - is the cheap, crappy interior. It makes my '90 Civic look like a luxury car. I'm not talking about shiny trim and such, but the overall quality. The Dakota interiors do not hold up well over time (well, at least the early ones). I'll deal with it as long as it runs and drives, though!

No rush on the measurements but it'd be great whenever you get a chance. I guess I need the length from the engine block mating surface back to where the transfer case bolts on so I can compare to the NP2500 currently in my truck.

Thanks to both of you for the responses!

 

The NV3500's slightly shorter length is something I'm going to have to make a decision about, eventually. My truck is still a project-in-progress so I've got some time before I'll get around to sliding the drive-shaft back in. I'm currently rebuilding the transfer case, but knowing the shaft is going to have a little less spline contact when it goes back in bothers me. Also, because I put a V8 in, I'm upping the torque that will be exerted on the drive line. I'll likely end up lengthening the shaft just to get that little extra length because, like you noted, finding the correct drive-shaft would be a chore with so many variations of transmissions and wheel bases.

 

Okay, I made the best measurements I could. The first time I tried to get a straight-across measurement like this.



For that measurement the end of the tape was located as such.



Then I tried to do one from the bellhousing/engine down to the transfer case like this. Probably less helpful but what the hell.



Just about dead on ***** 25" using this measurement.

 

Tbug, on your first measurement, it looks like you have a straight edge off the t-case mounting surface measured to the bell housing mount surface, is that correct? It looks like the total length on that one is a little less than 24.5 inches. Your next measurement slopes downward from the bell to the t-case, so I would guess it reads a little on the long side at 25 inches. Those measurements make it very similar to what I measured for the NV3500, at 24.5 inches.

Since both of these trannys were in use in 1st gen Daks in the mid 90's, it's understandable that the AX-15 and NV3500 would have similar dimensions. That would make it easier for Dodge to utilize the same cross member and attachment points in 4WD 5 spd trucks, regardless of whether the truck has a V6 or V8. So, I guess I'm just saying your measurements make good sense to me.

 

Weather permitting I'll measure my NP2500 this weekend and post for comparison. It sure would be nice to not have to replace or modify my rear drive shaft.

 

Yessir, that's correct. I tried to get the edge as straight as possible but I may have been a little off.

 

wjohn, I probably should have mentioned this earlier, but on the first page of my OCD Project thread ( https://dodgeforum.com/forum/1st-gen-dakota/380014-ocd-project-old-convertible-dakota.html )
I posted a drawing with a bunch of measurements I took of the NP/NV2500 and the NV3500. It might be a little hard to see, but everything's there; from mount locations to shifter location.

Yeah, we're probably both a "little off"; more than we care to admit anyway...