8-3/4 hard to turn the wheels

What oil did you put in it?
140 dyno oil is pretty syrupy. I never use that. I use 75W90

Normal on mine is; I can turn the driveshaft by one hand;(4 speed, and GVod). So, I am spinning everything inside the od box plus the MS in the 4-speed, with the two synchro assemblies, the driveshaft,the SureGrip thru the C&P,and the axles/drums/tires. But at 1/3.55 wheel speed.

In an automatic; turning the wheels, turns the MS in the trans,plus the planetary assemblies.
In the other direction, the sprague locks the low drum and then the planets are forced into action, spinning the low drum inside the band.
I think in one direction the sun shell spins, which then forces the whole front end to spin.
In any case, all those spinning things do require more power, as already said, in one direction, than in the other.

IMO, something is wrong, and I think it is seriously bad news.