Just finishing up w this 1st time rebuild w the help of video of Transmission Bench and atsg book for my model.
All bearings replaced... Along w a bad planetary gear set. Input shaft turns b it is very stiff...I figure because of all new clutch sets. I have lubricated all necessary parts either w fluid or high tack trans Assembly lube...any thoughts.

 

Since there are many possible reasons for excessive resistance in turning, I would suggest you open it back up and recheck your work.Things like selective thrust washers could get into the picture. There could be one clutch pack fiber disc out of place and not fully seated. Unless you check for complete seating /installation when assembling one disc not in place could do this.