This Massey-Ferguson Model MF135 Factory Parts Manual has exploded views of all parts on the tractor. With numbered pictures giving you great detail on assembly and disassembly. It also gives you a guide, with numbers, for ordering parts, and makes you seem much more informed when talking to the dealer.
Many service manuals, after telling you how to disassemble, in detail, and how to repair, will simply say reassemble. If you have your PTO in the wash tank, in 30 pieces, without notes, you have a problem. The parts manual can help you out with an exploded view of the PTO unit, and you can see immediately how it all goes back together. You need the parts manual!