Since you only jacked one wheel off the ground and are having difficulty rotating the wheel;
Is it possible that you have a SureGrip? jack both wheels off the ground and in any gear except park, and try rotating that wheel again. If both wheels now rotate in the same direction, then you DO have an SG .
But if the other wheel turns in the opposite direction then no SG.
And if there is still a lotta resistance, you should look into that.
No fluid in the trans is no big deal at this time, and is not a contributing factor.