I try to follow the manufacturer's service schedule, however when I don't it is usually because I have chosen to do items sooner than recommended. On the 50hr service I do what the book recommends plus the engine oil and filter and a complete greasing.
The filter part numbers are as follows:

Hydraulic Filter 6695918
Hydrostatic Filter 7375650
Engine Oil Filter 7384298
Fuel Filter 7374363
Air Filter 6666333