Seems like driving a 3 spd like a 6 speed is cause for excessive wear & tear using the OD. And since they seem to be scarce & hard to get rebuilt & pricey, does not make sense to me.

Better off doing what Tlowe does,run a 4 speed & use the OD, for the final gear.

Also using the OD on the 3 speed & use as a 6 speed seems like a crutch to make up for the poor gear spacing.
MBHD