8 3/4 rear end confusion

I have tried having someone rotate the driveshaft. I'll give it another shot tomorrow. So you're just saying to spin the driveshaft back and forth while someone is applying constant pressure on the axle inwards? When the car is in neutral, I'm pretty sure I can only spin the driveshaft one way. Even when I rotate the axle, which rotates the driveshaft, the axle will rotate one way but won't go the other way. So how would I go about rocking it back and forth? Also, I think there was a previous message in this thread stating that since I have a 73, they think I have a cone type sure grip which would mean there is no button to fall out of place. Thanks