I used a Novak adapter behind my Turbo 400. Keep in mind you WILL lose a good bit of driveshaft lenght(you'll need a new shaft, or have yours cut down) with the Turbo 400 and the adapter.
If you need a measurement let me know, I'll put a tape between the rear of the block and the T-case(for the lenght of the Turbo 400 with the adapter).
You will also need to fab a spacer to go between the adapter and the cross member, I think mine was about 2 1/4" tall.
[ 08-28-2001: Message edited by: southernfriedcj8 ]