If you take the old belts off and go to where ever....someplace that has a belt gauge....they can measure them and get an appropriate part # and sell you the belts that everyone makes that will fit the RRC and you can hang onto the old ones in the little sleeve that the new ones came in. You will then have a spare (in the truck right?) As well as the part # for it on the sleeve.
I have the #'s at the shop but in the name of owner paticipation and the big learning curve of how to buy parts for you rig....prolly should let you figure it out yourself.
Remember, like Ethan says,....nobody has parts for a Range Rover....but everyone does sell belts right?
...and the fan tensioner bolt (1/2") can be reached from under the truck with a long extension or the sum of several smaller ones.
DON'T lever on the PAS pump body to move the pump (if you dent it you WILL need a new pump)