Grampa gave me his truck

My grandfather recently gave me his 1992 chevrolet 1500 with a 6.2 liter diesel engine. He bought it new with just two miles on it. It now has just about 400000 miles on it. After spending time fixing brake lines and wheel cylinders I finally drove it only to realize something is wrong with the drive train. The truck reaches thirty mph and then the engine races and won’t change gears until I floor it. It does this every gear change until 65mph where it goes no faster. My grandpa did a lot to this truck to make it fast so it doesn’t take long to get there. Anyway I was thinking its either the transmission or the torque converter. My father in law also has a 1989 chevy 2500 with a blown gasoline engine and said I can take any parts from it that will fit. So if it is either of those things will I be able to transfer the parts from the2500 to my truck

This engine definitly was not one of GM’s best. It is quite an accomplishment getting 400K out of it, this must be some kind of record. It is tough to part with a gift from Grandpa but I think it is time to part with this truck and its diesel engine, just does not make sense money wise to put any in it.

I know I’m posting on my own question but I have to disagree with the last comment because yes this truck may have sentiment but I consider GM 1500 trucks with diesel engines my a sort of specialty of mine. And I’ve had one reach 450k and another one @ 320k and still going. Unfortunately I’ve never had any transmission problems in one and I’m rather inexperienced in the area of transmissions in general but I have nothing but time to work on this truck and If I can get parts free or cheap it will definitely be worth it to me. I know this particular truck won’t last forever but its not my daily driver and more of a project for me. I have a lot of plans for old Betsy. Including all new exhaust, rear suspension, and a some rust removal. My Grandpa would love nothing more than for me to restore her to her former glory. And I’m very determined to do so. So any helpful information for the task at hand would be wonderful. Thank you.

A free heavily modded diesel truck with 400k miles on it, and a faulty transmission.
I would have given it back to grandpa.

Replace the transmission if you actually want to keep it.

BC.

I personally helped with most of the mods. And yes I’d like to keep it I just wanted to know if the parts from the 2500 will work with little to no modding

Consider a used or rebuilt transmission. What engine is in the C2500? What transmissions are in the C1500 and C2500?

Sounds like a transmission problem and at that mileage would mean a complete overhaul.

While not being 100% sure off the top of my head, I think the transmsission from the 89 will fit your 92. This should be the 700R4/4L60 series transmsissions. Unless someone weighs in definitively you might contact a local transmission shop or salvage yard to verify the interchange.

Go to Ecololgy Auto Parts . com, its a wrecking yard, and they have a list of interchangeable parts. That might help. I get what you are doing, and I say right on my fellow shade tree mechanic. But you do need to know what transmissions you have, and if you can wait for TRANSSMAN to come on and post here, you will gain imeasurably as he is the tops on transmissions.

Hey I’m posting again for an update I’ve been putting the 2500s Tranny in for a little while (I got time but I gotta get the last little things done and get it away from the hay in the barn before it gets much colder here). I have a question is how in the hell am I supposed to put the transmission dipstick in. It looks near impossible and I don’t want to pull it all apart again just to drop the Tranny for this.