727 Hard to Roll backwards

No brakes on the car and when I removed the driveshaft the rear spun fine and the trans was still only rotating one way.

Called A&A as that was the rebuild kit and bolt in sprag I bought when I did the transmission in 2019/2020. They said based on the transmission working great for the 25-50 miles I drove it before blowing the car apart and the transmission hasn’t been used since (read over 2 years) they want to hear back once I get the brakes on and use the motor to back it up. Thought being maybe sitting has some stuck and just simply using it will break if free. So that’s what I’m going to do, try it once I get the brakes and things done.