Those letters are not part numbers, but casting letters, my Diesel 35 Parts Book lists 2 different conrods, the first "type" is part number 2A375 which the book says "was not serviced", I assume meaning not available as a spare part, the second "type" is 2B618 (2B0618 is the "new" part number), which was also used on the early RD6 tractors, serial number 2H1 - 2H958. Looking at the RD6 parts number book there were several changes made to the conrods after that one, and maybe someone can chime in with info on whether they were all interchangeable. The piston size changed from 5.25" in the D35 to 5.75 in the RD6, so I assume the conrods needed extra strength as the motors gained extra HP.
I have a Diesel 35 with a broken #3 conrod, so I'm interested in hearing how you get on.
regards
Mike
Maybe the place in CA has one that Kent gave you the name of. Also The guy I got my fuel pumps from might have one as he said he had some diesel 35 parts.
The 2A0375 rod is replaced by a 4H8651
The 2B0618 rod is replaced by a 5B1294
Gets pretty messy as there seems to be a bunch of equivalent rods as well as these and are apparently all insert type bearing users. Hopefully you can get with a knowledgable Cat parts man to help sort it out.