Th400 to 700R4(?) '87 3/4 ton Crew cab

[southside_jon]

I'm new to the sit and in searching it...I have found that I know a few people on here already. (some people back in Kansas). Anywho...

The TH400 Tranny in my truck was taking way to long to shift, and when it did, it would be a hard shift. (this is why my ol'man sold it to me for $500). But it didn't seam to slip. Hell I even drove it all the way out here to Cali from Kansas, loaded down with my Harley, my tool box, and all my tools. No problems other than a hard shift from 1st. to 2nd.

Long sotory short.....it finally went south yesterday.

Now the question; Replacing the TH400 would be the easy solution, but I would like to switch to an Over-drive tranny.

My brother back in Kansas has a '92 GMC with a good OD Tranny. Can anyone tell me what tranny that might be and if it would perform good in my truck?

My Truck;
1987 GMC 3/4 Ton Crew Cab 2wd, long bed, TH400, and 4.10 gears out back.

The Donor Truck;
1992 1/2 ton ext cab, Over drive Trans (?), That's all I know about it.

If this tranny will do for me, I was currious about crossmember, Lock-up, and all the common questions in the swap.

Oh yea it's a 3/4 ton but I don't plan on hauling anything heavyer than mine or friends Motorcycles. nothing like a 5,ooo trailor.

I would like to have a crusier. Maybe lowered and custom wheels one day.

Any help and guidence would be great

Thanks, Jon

[old Rusty C10]

i do know it is possible to do the swap BUT you will need to get a controller for the trans for it to work.. I think you will have to move your existing crossmember to get this to work but you do get to reuse your old one... Someone else can chime in here and give the particulars. Ive never done this kind of thing BUT its been done here many times before so im kinda clueless on it..

[southside_jon]

Thank you for the response. I've been told that the 4L80E would be a better trans for my truck. (on my welcome thread) Any Ideas on this sawp?

[old Rusty C10]

you may want to post this in the drivetrain section also

[BIG10]

The tranny in the 92 is probably a 4L60E, electronically controlled. Like Rusty said above, you'd need the computer to control it. If you're not doing any heavy towing, you don't need a 4L80E. A simpler fix would be to just find a 700R4 locally. They are readily available at fair prices. My 700R4 has been abused for many years without problems. Good luck either way.