Rayin"S" posted:I just took a look inside my SD-70, a measurement inside the body in the location of the motor is 1 inch. A measurement over the round part of the motor yielded approximately .960 inch. The motor in the SD is not a round motor but rather has flats that run parallel to the length of the engine. The flats appear to be a smaller measurement than the flywheel which measures approx. .780 inch.
Ray
The inside width of a GP body is 24.38mm, tad under an inch and the SD motor across the flats is 19.30mm, so there is room to put one in if the motor is fixed like the SD and have room for wires to run by it as well, so it could possibly be done.