Whats the best transmission swaps?

[z71HalfTon]

So I have a 1994 k2500 light duty with a tbi 305 and 4l60e, and I eventually want to swap to a 350 but haven't decided on what tranny to do. So I was wondering what are my best options? I don't want anything crazy hard but I don't care if it's manual or auto.

 

[jigsaw]

4l80 is the most popular

 

[NickTransmissions]

So I have a 1994 k2500 light duty with a tbi 305 and 4l60e, and I eventually want to swap to a 350 but haven't decided on what tranny to do. So I was wondering what are my best options? I don't want anything crazy hard but I don't care if it's manual or auto.

The best transmission swap is the one you don't have to do. Anything wrong woth your current trans?

How much power will your 350 be making (ball park) and how will you use the vehicle (daily driver, moderate to heavy towing, off-road, etc)?

 

[Awest623]

The easiest manual transmissions are going to be the NV4500, NV3500, and SM465. They all came stock in these trucks and are basically plug-and-play to get driving. You can spend time cleaning up wiring harnesses and adjusting the tune to work better with a manual, but all of that is absolutely not required to go down the highway.

I put an NV4500 in my 98 5.7 K1500, best thing I ever did. But keep in mind it's a TRUCK transmission. Granny low 1st, wide spaced 2-4, 5th gear overdrive. The granny low is real nice for tight and steep trails, and the wide spacing hasn't given me any issues. For everyday driving it's basically a 4 speed, I hardly ever use 1st gear because it's so low.

For a closer spaced (car-like) tranny without granny low, an nv3500 will also work, you won't hurt it with a stock 5.7. 4x4 NV3500s are a lot easier to find than the NV4500s as well, took me about 2 years of casual searching to find my 240k mile 4x4 NV4500 transmission. I held out for the NV4500 because I wanted one that would hold up after grenading 3 4l60Es. Even after 240k miles in a different truck it still shifts smooth with original synchros.

I don't know anything about the SM465.

As others have said the 4l80e is the most popular one for guys wanting a stronger automatic transmission. They can handle a lot of power and a lot of abuse.

 

[Awest623]

You can also get into more custom stuff with a 4l65E, 4l85E, T56, TKX, TR-4050, etc.

 

[z71HalfTon]

The best transmission swap is the one you don't have to do. Anything wrong woth your current trans?

How much power will your 350 be making (ball park) and how will you use the vehicle (daily driver, moderate to heavy towing, off-road, etc)?

Thanks for the replies guys! Right now I'm just daily driving my truck so I will keep the 4l60e but eventually I want to get another obs and use this one as my offroad/hunting rig, so I like the idea of a manual for reliability. My tbi350 will be making stock power.

 

[99xcss4]

if you want a manual the early nv4500 is what you want external slave cylinder and lower gear set you will also need to change the input shaft on your t-case or get a t-case with a 32 spline input shaft you may need to modify your driveshafts or get different ones you will need a different transmission crossmember a clutch master cylinder and a clutch/bake peddle assembly and cut a hole in the floor for the shifter

 

[z71HalfTon]

if you want a manual the early nv4500 is what you want external slave cylinder and lower gear set you will also need to change the input shaft on your t-case or get a t-case with a 32 spline input shaft you may need to modify your driveshafts or get different ones you will need a different transmission crossmember a clutch master cylinder and a clutch/bake peddle assembly and cut a hole in the floor for the shifter

Thanks for the info! What years do you mean by "early" and would a nv3500 be about the same swap in terms of difficulty?

 

[99xcss4]

What years do you mean by "early" and would a nv3500 be about the same swap in terms of difficulty?

91 92 and 93 it should be rpo code mt8 as far as how hard it is to swap a nv3500 compared to a nv4500 I do not really know

 

[99xcss4]

here is a listing for a reman https://www.4ws.com/product/nv4500-...4-pickup-4x4-5-speed-zumbrota-drivetrainwhile it say it if for 91-94 it is the 91-93

1991-1994 RPO MT8 Features​

• GM NV4500 Transmission to bellhousing bolt pattern (not the same as GM 4-speeds)
• Right hand mounted hydraulic slave cylinder with fork mounted throw-out bearing
• 1991-93 1st and reverse not synchronized

1	2	3	4	5	R
6.34 (1991-1993) 5.61 (1994 on)	3.44	1.71	1.00	0.73	6.34 (1991-1993) 5.61 (1994 on)