The REAR section of a 5-ton transmission PTO is the same as the REAR section of a 2 1/2 ton transmission PTO.
You have two options for installing a PTO driven pump. Well, maybe 3.
If you have the transmission PTO for the winch, double check to see if it has the rear facing PTO, that can be used. (this is what my truck uses) If not, then a rear section can be found on 5-tons or 2 1/2 tons.
If you have the transmission PTO, and no winch, you can drive something off the front on the PTO, just takes more fab work. I've heard of running a winch and dump off the front PTO by putting a sprocket on the driveshaft to a pump.
Can also use a transfer case PTO unit, usually found on tank/fire/crane trucks.
Here's a thread on dumping deuces. Just search dump conversion or bed, it's a popular subject.
http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=3303