Originally Posted by Supercharged SS
Why do you want to ditch the 6l80e? It's a great trans with the right people behind it.
Matt at FSP would be who you should contact about installing the 4l. Although he went from an m6 to the 4l, he'll know exactly what's needed to make it work.
Put down some real power Jamie and you'll think twice about saying that LOL.
Either way, yes I had a 4L60E in my car (Swapped in from a m6), so there are a few more items to take care of when swapping into a factory 6l80e car. Short list..
Trans Crossmember & Poly Mount
Driveshaft custom length (I can get you one from DSS)
Auto vs. Manual valve Body (Electronics?)
I have the stock 6L80E shifter in the car, with the stock shift rod. You'll need to do a bit of massaging to the stock shift rod to make it work. From my knowledge no one has made a trans crossmember yet, Doug @ ECS made mine for me one-off.
Also, the 4L60E requires you to massage the floorboards in on the passenger side tunnel (Yes get out the big hammer).