Fred,just a thought on the Blazer motor. I don't know if this would work, or if it would damage the motor, or even fit. That being said, if the motor was not grounded in any way to the Jeep, reversing the polarity of the DC motor would make it run in the opposite direction.
You could always pick one up, for the fitment, and maybe PM John Strenk (sp).
1957 WILLYS pickup,
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac.
1980 CJ5 trail Jeep.
1989 YJ the CJ to YJ.