I picked up a used RBW hitch and got the manual off of the net but I can't figure out how far in front of the axle the pin should be placed. Truck is a 2000 supercab with a 6.5 ft box. The person I bought the camper from had his Reese set at 3/4" ahead of the axle on his Chev. Any ideas would help.

 

Acceptable is directly over the center line of the axle to 2-3" in front of the axle.
This is the standard for most bed mount hitches.

Most hitches that are designed for a specific spot are usually 1-2" in front of the axle center line.

Hope this helps

Be careful with the '97-'03 trucks. They have the weakest frames above the rear axle. I hope you don't have a big trailer.
You may also need a kingpin offset to get the trailer away from the truck in a short bed.

 

I think I'll aim for an inch ahead of the axle. With the price of gas at 1.38 a liter I won't have to worry about towing it too far. Thanks Osprey.