I believe I have a getrag 290 nv3500. Got it out of a junkyard and the guy behind the counter says it wasn't the same but would work. I used it for many years and now am going to rebuild it. Diagram show the same part number for all three synchro sleeves but upon dismantle its clear that the 1-2 sleeve is different and even calls out which side is first gear also has what appears to be a part number, but all of my searches come up empty. can someone help identify this sleeve so I order the correct one? The 1-2 reads "005.8.5052.20 FIRST GEAR SIDE"
This is in a 1989 GMC C1500 4.3L

 

It’s possible the sleeves have been updated and are the same size with service parts.

The NV3500 can be identified by the number stamped on the front or rear of the right (passenger) side of the transmission - it will be a P (identifies the NV3500) followed by a digit (identifies the model year). The description says it’s at the housing joints.

If it really comes to it, call your local dealer parts department - they won’t be able to reference the VIN for ID but they can still look up parts and should at least be able to give you a part#.

 

This is great help I will be able to positively identify with this information thanks gumby22

 

ok. the marking on the case reads M04. ID?

 

Is that the only number on the case? I’m not finding anything in the service manual for that - the only other stock option it shows is the GM 117 and that’s identified with an “N”

In the mean time I did find this as I was researching - maybe it will help.

https://documents.holley.com/techlibrary_manual.pdf

 

 

Ok this is getting ridiculous. I’m still not having any luck with the “M04.”

The GM numbers ending in 304/305 are casting numbers for the case only - GM used them for 3 or 4 different transmissions.

I did find this thread on another board that discusses some of the differences to look for but I haven’t had time to verify any of this information -

http://67-72chevytrucks.com/vboard/s...d.php?t=371403

I’ll keep digging on the M04 as I have time.

 

Yeah this transmission definitely has three shift rails. I have been in contact with a rep from a local transmission parts shop. Sent pictures of the bearings and sleeves. He's pretty confident that he can figure it out. I will post the results of at least the rebuild kit we decide on.

 

The rebuild kit we went with is a BK235AWS and the parts that arrived look right. I am still having trouble finding a diagram and parts list as I still don't know exact part number for the synchro sliders I believe this means its a 5LM60 early but nv3500 stuff is all I can find. The 1-2 dont look that bad so I will just try the 290-15 PN and hopefully it will work.

 

The most I’ve been able to verify is the NV3500 wasn’t introduced until about 1993 - if the donor truck was pre-1993, it would be a 5LM60.

I’ve had no luck with identifying the M04.

I know it’s not ideal but if it really came down to it, you can reuse the synchro sleeve if it’s in good enough shape.