more 555 questions

[robert]

Hello everyone. OK, im rebuilding my trans in the "frankinloader". I have contacted twindisc, they sent me a large parts file for this transmission. According to the model # I have, twindisc inc. says its a JD-550-B loader. digitup says its an old 555. here are some pics http://photobucket.com/robertfk
could it be a 555B, or just a straight 555? Isnt the 550 a dozer? Looking at both the 555A, and B service manuals i cannot tell any differences. Both manuals have the same tans. With no ID tag, its been a bit of a struggle identifying this machine.