1993 GMC Sierra 1500
350/4L60E/342 rear end
First and second are starting to slip some. I know I'm on borrowed time now. I want to swap it for the 4L80E transmission because I know they will bolt up to the 350 engine. For some strange reason they put 350's in the 3500 model trucks and put 4L80E's behind them, so I know it will work in my truck. What are the changes I'll need to make for it to work and shift like it should, and is it worth the money? My truck isn't junk like most other trucks of that model. Body and paint is good, two tone. Good looking truck. Rebuilt engine .040 over. Less than 50k on the engine.
What are the changes I'll need to make
it'll need a matching computer
is it worth the money
That depends. How much money?
4L80 is probably overkill on 1/2 ton truck. You have a light duty axle and suspension. If you need that much strength, then you should have the right chassis to go with it.
So it would be better to rebuild it with a better parts?
it lasted 30 years. Is that not good enough?
I just don't like them honestly. They don't have a good reputation either. Maybe the newer ones after 96, but when they first came out they were trash. I'm the second owner. First owner was an old man, bought it brand new in 93 and piddled around in it. I'm not like that. I've built the engine for performance. That definitely is what has my trans slipping I'm sure. The 4L60E just can't take it.
If it were mine, I would look at Gearstar, TCI and Monster for extremely well built 4l60E transmissions with all updated parts and all weak spots addressed. They come in stock and built to the hilt versions, with warranties. Then you can just swap it out.
That is something I haven't thought about. I'll compare prices of that and swapping for the 80. I just read on Motortrend where all I will need is to buy a cross member that will support it, trans lines, an adapter for the harness, and another yoke. Says ECM computer will know what to do with no changes to it(first I've heard of that, but okay.) I'm all for keeping the 60 if the bugs are worked out like you said. I'll just see what's cheaper. Thank you for the advice.
Sorry, another yoke as in another driveshaft with a larger yoke. Got to typing too fast and left that part out.
You said you've got an essentially new motor. With a decent rebuilt trans and regular maintenance you could easily expect another 200K miles out of it. I put a rebuilt engine and trans in my '81 Toyota pickup that I paid $2400 for in 1991. Last week, a guy offered me $9000 for it. I politely declined.
That's a Toyota though, best vehicles on the road. Definition of quality lol. GM and the 4L60E can't say the same.