From making the mounts myself for a flipped VNT for mk2 I found some things out. IIRC I think the differences are in the cast aluminum piece. The bolt holes are the same in all, but there is one that is about 7/16" longer than the other. FWIW I think you could get it to work no matter what you have, but the one that works I am pretty sure has an A at the end of the 9 digit part number.