No difference I think Terry. The title of the older manuals was "Serviceman's Reference", and like a service manual, was the instructions with numbered diagrams and illustrations for how to disassemble/reassemble the tractor and its components
I have a D8 Tractor Sevicemen's Reference Book. It does not indicate that is for the 2U or for which serial numbers. Not sure if it will work for you.
Bruce
Bruce - I'm 71, so both the manual and I are survivors!
I've an "operation and maintenance manual" on the way from 657cat. It's coming from Canada, so no idea when it will arrive. When it does, we can compare notes and see if we can further identify yours. Seems like, by the title it should cover all D8s 1953 and older - but that's a lot of models... I'm just a newbie - what do I know?!?
From what I've been able to learn 1955 was the last of the 13000 engines - so the engine would be correct. I believe my D8 2U 13752 is considerably older - a 5-speed, but not a wet clutch.
I do not think that what I have would do you much good if you are just trying to get the machine running to determine if you are going to purchase it. If you purchase and then need to dismantle and overhaul, then it would be somewhat useful.