The stoker motor is a Dayton (Grainger) 6Z075, 1/80Hp, 4.5RPM, 100 In# torque, PSC, Ball and needle bearing. Here is a link to it: http://www.grainger.com/Grainger/wwg/pr ... submit.y=0
Not sure what you plan on building, the Harman uses a solid aluminum pusher block to push the coal up a ramp and onto the burn plate, kind of a cross between an undrfed stoker such as an EFM or Van Wert and a carpet stoker such as a Keystoker.
You may be better off looking for a used unit that you could scavenge the parts you need.
Hope this helps