About turning a 3 speed around backward, or any transmission for that matter. I would be hesitant if it had helical gears, because helical gears by design make some end thrust, and this thrust is handled in the design of the bearings or thrust washers in the transmission. If the transmission turns the opposite from designed way, then those plans for thrust management go out the window.
If the transmission has straight cut gears it may work, as there is essentially no end thrust created by the gears.
I did look into using a Spicer 3053a military surplus 5 speed OD transmission as an auxiliary (installed the normal way). I have not done it, and don't plan to, but did come up with a plan to make it work, other than shift linkage and mounts one piece would need to be machined, and not terribly difficult. The shift linkage should work from a Spicer in a COE application, even from a 10 speed or larger, as the shift towers are supposed to be the same.
The plan I had could work for other transmissions as well, but a large input shaft would be good, 1.5", 1.75", or 2" would be even better.
Grigg
