I hear of people swapping in a few overdrive transmissions, but it was my understanding that the olds is a different bolt pattern than tbe chevy. What are people doing to swap 4l60 or 4l80s? What is involved in the electrical end? Aftermarket controller? I see Edelbrock makes a controller for around 700ish. What other options are there for controllers? I would prefer something bulletproof and I really don’t have confidence in a 700r4.

 

These days, the 4L80E is your best choice. It's really just a TH400 with an extra overdrive section between the front pump and the rest of the trans. It actually fits better in an A-body tunnel than the 700R4/4L60 due to the large wart of a servo on the passenger side of that trans. The 4L80L is longer than the TH400 and requires a custom driveshaft, but given the difficulty in getting some 200-4R parts these days, it's probably your best choice. Yes, you need a trans adapter and a computer to control it. Those items are readily available.

 

Gearvendors is an option

 

What are some sources and makers for the adapters and controlers?

 

I forgot about them. That may make the most sense if the th400 is sound

 

I have a gear vender on my car, if I had to do it over today I’d go 4L80 without a doubt. The lockup converter and programmable shift characteristics is a win win.

im betting you could buy a 4l80 core, have it rebuilt, but the aftermarket controller and adapter cheaper than a gear vender.

If your existing trans is tired or has a lot of miles on it and needs rebuilt, without a doubt go 4L80.

 

Don't by the flimsy adapters, this one is better built. Basically go with a controller that has the features you want and has goid reviews. As said, a 4L80E is a no brainer. Any trans will require mods in place of the TH400, good call on skipping the 4L60-70E. They didn't hold up behind stock behind a 5.3 LS, even modded versions are questionable behind a 455.
https://www.summitracing.com/parts/trd-0061