That filter in front of the radiator is the primary fuel filter. It should have a see though cup at the bottom to drain the water.
Here is a PDF from Cat:
http://ohe.cat.com/cda/files/517742/7/LEHT9288.pdf
The part number is 175-2949. There is also a secondary fuel filter with you will need to go under the engine to see and service, along with the oil filter.
I believe all CAT RV engine has the shallow sump (19 Qts).
PM Parts Reference
Oil Filter - Advanced Efficiency 1R1807
Filter Group with Water Separator 175-2949
Fuel Filter (secondary) 1R0751
Filter Kit (Antifreeze) 173-5326
Filter Kit [Extended Life Coolant (ELC)] 173-5325
Liquid Conditioner for Antifreeze 6V-3542
Test Kit for Antifreeze 8T5296
Test Kit for ELC 172-8851