The whole system is a Rugby 2.5. It was added by the former owner so I don't know much about it. The pump and hyd tank is towards the rear between the frame rails. The pivots are welded to the frame at the extreme rear and the control is a push button deal in the cab. It will go up a lot farther than shown in the photos, that is just up enough for the hay to slide out.
The rear bumperettes had to be removed so the bed could swing downwards as the bed hit them and the front mudflaps had to be removed as they would hit the tank and spare tire. The rear mudflaps are just standard rubber ones in place of the stock ones.
The old owner said it would lift with about anything in in, but that a full load of wet sand would trip the breaker on the system. About all I have hauled is hay so far and it lifts a ton of hay like it does not even know it is there.
My guess is that the 2.5 means 2.5 ton lift.
http://www.rugbymfg.com/rugby-pdf/Truck%20Hoists.pdf
ETA: Found a link to Rugby. Mine is an LR25