[Mike C]

There is a big block manual trans crossmember. It is a different shape than the small block one because it mounts higher up the frame and closer to the front. Unlike the auto trans x member that can be slid forward and backwards, the upward curve of the frame requires a different size/shape for the big block bellhousing crossmember.

Some of the clutch linkage components are different as well. I think the z bar pivot bracket the same but mounts further forward. Both sets of holes should be in the frame.

High hump also has the 4 speed shifter opening cut in a different location and I believe the big block shifter cane is different as well because it is so far under the dash.