Dave Ross, Dennis,
Dennis, I think he is asking about the adjusting brace, and not the mount bracket.
Dave, if so, there is not any difference. It depends on which parts look up you use. In the one above, it comes up as NLA on one of them, and it also gives a Kohler P/N for one and a couple of NLA updated P/N's, for one of them. If you go back to the original IH part numbers for them, they are both the same number, 377 893 R91 Bracket, Motor-Generator Adjusting. Kohler number is KH 231273. The IH numbers could have been updated to Cub Cadet Corp numbers more than once and could explain why you found different numbers. Going from memory, I think the only one that is different is the model 86, and both the mount and the adjusting bracket is different. The early Originals used a welded together mount rather than the cast mount used later.