This is correct information
I believe they are all the same. the only thing is early and late E body's won't interchange I think 73@74 cross members are different.
Here are the applications and part numbers for the trans crossmembers. Each part number is correct for automatic or manual transmission
70 E-Body part # 2962074
71 E & B-Body built up to June part # 2962074
71 E & B-Body built after June part # 3583188
72 E & B-Body part # 3583188
73-74 E & B-Body part # 3642794
70-72 E-Body & 71-72 B-Body will interchange but 73 -74 will not interchange with a 70-72 E or 71-72 B
Hope this info helps with your search so you get the correct part