I'll try and dig them up and post some pics. Some of them have part numbers on them - and maybe we can confirm. Like I said, they look exactly the same to me. Its just been so long since I did that research, its fading a bit.
All the cars I looked at in the junkyards with the A6 (long) compressors seemed to be the same for the 400's and 455's if they were from the mid to late 70's. Some of the 301's have the R4 (more shallow) compressors and of course those won't fit on the earlier A6 compressors. I don't think they had the L-shaped bracket.