Since I found I had a belt missing this week I decide to put a couple of new ones on my M813. Good luck finding a fan belt. Everyone calls them main drive belts. I could find no reference to a main drive belt but I did find the fan belts. They are just called belts in the table of contents.
After checking the manuals:
http://www.steelsoldiers.com/upload/809/TM9-2320-260-20.pdf
and
http://www.steelsoldiers.com/upload/809/TM9-2320-260-34P1.pdf
I decided to update the current part numbers with a more fitting description for the slow kids like ME.
There are 7 (yes seven) belts on an NHC-250 Cummins in a 5-ton M809 series truck.
Water pump belt (only one). It is the belt all the way towards the back of the accessory drive pulley. This belt goes from the accessory drive pulley to the water pump.
http://www.steelsoldiers.com/upload/809/TM9-2320-260-34P1.pdf
Sec II fig 89 item 1
Car Quest TR22425 Napa 2522425 Waterpump (1) belt
Power steering belts (yes, two). These are next two belts in front of the water pump belt. They go from the accessory drive to the power steering pump.
http://www.steelsoldiers.com/upload/809/TM9-2320-260-34P1.pdf
Sec II fig 219 item 7
Car Quest 13A11p5 Napa 259470 Powersteering (2) belts
Fan belts (yes, two). These are the last two belts on the front of the power steering belts. They run from the accessory drive pulley to the front two grooves on the 4-groove fan pulley.
http://www.steelsoldiers.com/upload/809/TM9-2320-260-34P1.pdf
Sec II fig 90 item 16
Car Quest TR22401 Napa 2522401 Fan (a.k.a. main drive belt) (2) belts
Alternator belts (yes, two). These are the back two belts in the fan pulley. They go from the fan pulley to the alternator pulley.
http://www.steelsoldiers.com/upload/809/TM9-2320-260-34P1.pdf
Sec II fig 91 item 10
Car Quest 11A0915 Napa 257360 Generator (2) belts
If there is a mistake by all means let me know and I will correct it.
Oh yeah, how did I find all this stuff? Take a guess.