I bought a 643 out of a wrecked Ford school bus about 25 years ago. I remember when I called Stewart and Stevenson about a PTO for a hydraulic 5th wheel, they never asked me if it had a drive gear. I just put the PTO on and shimmed it like any other PTO. I now have a yard truck with a 6v53 and an Allison of some sort. It also has a pto driven hydraulic pump.
