nv3500 to nv4500???

[big72red]

Hey guys, I recently picked up a '95 K1500 that is currently my daily driver. The truck has the NV3500 5spd trans and, I believe, the NP241 transfer case. The truck has a pretty stout 350 in it. I'd estimate 375-400hp. I've never heard anything but horror stories about this particular gearbox being the weak link in the drivetrain. that being said, it seems to be doing fine so far. I do have a few questions though...

1. Will this tranny be tough enough to handle my power level and 33 inch tires? I don't really drive it hard, just normal driving and light towing.

2. The only problem I am having is that I can't select reverse without a slight grinding of the gears. All forward gears are fine. Does anyone have any advice on that?

3. I'd really like to swap in an NV4500 and be done with it. Will the NV4500 just bolt right in place of the NV3500? Will I need driveshafts shortened/lengthened?

Thanks in advance for any input guys. You all have been very helpful in the past.

[big72red]

C'mon you guys...I know at least one of y'all has some answers/experience with this. I could really use your input before I drop $1000-$1200 on an NV4500. I could sure use that cash elsewhere, if my original trans will hold up. I'd greatly appreciate your advice.

[DirtyLarry]

I am about 90% sure a NV4500 is a direct swap in place of a 3500. If I recall the 3500 and 4500 overall length is the same. The tcase spline count should be the same as well. Many 92-95 1500’ series 4x4's actually came with NV4500’s before the NV3500 became so widely used. There was about 3 years after GM canned the Getrag and used the 4500 in 1500 series trucks until the 3500 came on the scene.

I had a NV3500 in a ’98 K1500 ECSB Z71 and hated that trans. Traded that truck for my ’01 HD back in 2001.

[Hoods69BadBowTie]

I am curious as to this as well cause I have the 3500 in my truck right now. It works good its just old and tired when it finally goes out I want to put the 4500 in. I have heard there are some differences but not a 100% sure either way.

[hatzie]

If you have an NP231 it will not bolt up because it's a 27 spline input. The NP241 should be 32 spline and it will bolt up.

You may have to change the crossmember location and driveshaft.

There is no gap in production from the 5LM60 to the NV3500. GM started using the NV3500 in the CK1500 and S10 with 4.3L V6 when the NV3500 entered production in 1992. The CK1500 with a stock NV4500 is a rare beast.

[dishow]

Originally Posted by hatzie

If you have an NP231 it will not bolt up because it's a 27 spline input. The NP241 should be 32 spline and it will bolt up.

You may have to change the crossmember location and driveshaft.

There is no gap in production from the 5LM60 to the NV3500. GM started using the NV3500 in the CK1500 and S10 with 4.3L V6 when the NV3500 entered production in 1992. The CK1500 with a stock NV4500 is a rare beast.

the np241 in the auto is a 28 spline. the np241 mated to a manual is a 32 spline.have both in my garage.

[hatzie]

Originally Posted by dishow

the np241 in the auto is a 28 spline. the np241 mated to a manual is a 32 spline.have both in my garage.

He has a NV3500 manual. So. In his rig If it's a NP231 it's 27 spline and if he has the NP241 it's 32. IDK If GM put the NP241 behind the NV3500 in the fullsize light trucks.

GM New Process 241 Transfer Case

"In 1988, GM began using the NP241 transfer cases. Most of these units will be right hand drop, but Chevy also used a few left hand drop applications. The Chevy NP241 is supplied with a 27 spline female input or a 32 spline female input. With a T350, 4L60E or 700R4 tranny, it will be 27 spline. With a T400 or 4L80E trans or 5 speed, it will be 32 spline."
high-impact.net/transmission_and_gear/Tcase_NP241.htm

GM New Process 231 Transfer Case

"Most of these units will be right hand drop, but Chevy also used a few left hand drop applications. The Chevy NP231 is supplied with a 27 spline female input."
high-impact.net/transmission_and_gear/Tcase_NP231.htm

[big72red]

Thanks a lot guys. I do have the NP241 transfer case. I was pretty sure it would just bolt right up. I'll just hafta figure out about the driveshaft lengths. Does anyone know what a reasonable price for a non-rebuilt GM NV4500 would be? I'm finding a lot of rebuilt ones for $1000-$1300. That's a little too steep for my budget right now, so I'm looking for a used NV4500 for a junkyard. Anyone have a ballpark figure?

[hatzie]

I paid $900 for a 1999 NV4500 from a totaled K3500 diesel with 38k on the clock. I put it behind a 6.5 Turbodiesel in a 76 K20. Unfortunately the 4500 is popular so it's not a cheap transmission.

I've heard the horror stories as well. I bet they are referring to the 88-92 5LM60 and MG290 that had some pretty serious engineering deficiencies.

If you don't intend to tow significantly with it and it's OK now I wouldn't change it out. My stepdad is a logger and he beat the crap out of a 1997 K1500 with a 350 and NV3500 for close to 270,000 miles. Picture driving off road where the log skidders have barely made a path for a truck over small downed trees and big rocks. A log bashed a small hole in the oil pan and the oil leaked out slowly enough that it spun a bearing about the same time the check gauges light lit. The tranny was still kicking.

[big72red]

In that case, I might just let it ride for the time being. I don't ever intend to tow more than 3500-4000lbs. (bass boat) with it. I just wish I could figure out why it's a b**** to get into reverse. I could understand bad synchros in forward gears, but they are all fine. Thanks for the advice guys.