Lots of options even now for the SM420 transmission. It depends on how much torque, or HP, and what speed (RPM) you need from the PTO shaft. What are you going to run? Muncie or Chelsea? modern or vintage? A modern Chelsea Single-gear PTO part # 100XRBJX-W3XA is one: shaft rotates same as engine rotation at 54% engine speed, has 7/8" dia. keyed output shaft and a cable or lever shift. Good for 125 ft-lb of torque at 1000 rpm. Good for dump hoist, etc. Search the swap meet or better maybe run an ad under parts wanted. One of the most important things about PTOs is the drive gear in the trans. PTO gear must match, hence a **** PTO is not likely to work on a GM trans.


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