This is 30 Volts, 140 Amps direct current generator. I bought it few years ago as military surplus and it was stored unused in my garage. It was built by Electric Auto Lite Co. It has 2275 to 4500 rpm. It fits to 4 1/8" hole and has 5" BC mounting holes, for 3/8 bolts. The shaft has 7/8" diameter and 16 splines. It comes with 4 3/8 inch long coupling. One end of coupling fits on generator shaft and another has a 1 3/8 inch hole with 5/16 inch keyway. It can also be used as variable speed motor, as picture shown.