For 757:
Engine driven pump: 1 providing left hydraulic system; 1 providing right. Located 1 on each engine gearbox.
Electric ACMP: 2 providing center system, located in hydraulic servicing bay. Another 2 for left and right system, located left and right wheel well bay. For center system, only 1 pump can operate at a time.
Hydraulic driven motors: 1 PTU in left wheel well, powering left system from right I think (I'm sorry, too much 767 in my head for the moment). There can also be an optional HMG for generation of electrics.
Are there any others? Yes, the Ram air turbine has a pump providing the center system.
767 is almost the same, except PTU only providing stab trim, center system has an extra air driven pump and left & right acmp's are in pylon and center acmp's are in right wheel well. Both center acmp's can run at the same time here