I just pulled my 3000 TCI out of my 350 turbo tranny. I was planing on buying a custom built convertor to go from my ls1 to my 350 turbo. BUT... it turns out my TCI I have now lines up w/ the inside holes of my 98 flywheel and lines up w/ the out side holes of a 4l80e flywheel. The shaft coming out of the convertor is the same as a 4l60e and fits perfect into the ls1 crank.

Heres some pics!!