Are the wheels just turning slowly? Can you stop them by hand? If so thats pretty normal. If the forward clutch was applied incorrectly in N/P, then it would actually be in 1st gear. If the kickdown band was to tight it would be in 2nd gear. In either case reverse would be bound up and the other forward gears wouldn't function. If all gears function and it shifts correctly you should be fine.
Doug
This ^^^^^ the output will turn if there is no driveshaft and the wheels are not on the ground , I had the same thing happen with a duster I had a long time ago with the rear tires off the ground , I was able to stop the wheel from turning with my foot.
