I am still confused about the backplate assembly itself. Was the version that I have with the separate mounting bracket the "A" version of 29773-02? Was one of the letter revisions B or C when they went to the one piece backplate? I would think that would be enough of a difference that it would get a whole new part number, but what the hell do I know? Just trying to make sure I know exactly what I have here.

 

all the letter at the end means is they updated the part in some way so it is not unusual to have what you have. Actually some like your back plate better then the updated ones because it is easier on your plate to vent the headbreathers to the ground instead of directly back into your combustion chamber.