6L80/6L90 swaps - trans tunnel mods?

[Jackson's Dad 64 C10]

Originally Posted by raic65

I'm running the same setup (LY6/6L90) on my 66 c10. I fabricated adapter plates for the motor mounts that placed the #8 coil within 1/4" of the firewall. I also fabricated my own transmission mount. I set the engine/transmission down at 3 degrees. With that said, my c10 has the factory high hump and the 6L90 clears with plenty of room. In my opinion, if you need to replace the floor, the high hump is all you need. Most of the height in the 6L90 is actually below the input/output shaft centerline IIRC from my research.

Raic65, that’s really good information. Did you keep the truck pan on the transmission, or did you swap to one of the lower profile pans like a Pontiac G8? I’m just wondering if I’m going to have to deal with a really low pan below the frame rails. Thanks for the input!