C50 dump truck information

[olyeller]

Where can I find information about the hydraulic system on the C50 dump trucks? The service manual doesn't say anything about it, so maybe they were fitted after the factory? Anyway, the hoist doesn't start lifting until about 5-15 seconds after you engage the PTO. Maybe this is normal as the pressure is building up. Wasn't sure if that meant a worn pump or not. Seems to lift at the same speed regardless of load. I know the pump is a Chelsea but I don't know how everything fits together (there's a driveshaft running from the pump mounted on the transmission to the hydraulic reservoir, not sure what does what). It's also leaking pretty bad. Pump is mounted on the transmission, so that turns the PTO shaft, but does that thing also run the hydraulic oil through it? I pretty much know the answer already, but how does it work?

Thanks