Slamming between gears on an automatic

My 95 saturn SL slams when i put it into reverse after driving it for awhile and now is doing the same thing when I'm accelerating or slowing down. I put the car into reverse, then a few seconds later it slams really hard and then i can finally back up. When driving, it is more of kick. Any ideas?

It is most likey a loose input shaft nut, but you should search on saturnfans.com

It is most likey a loose input shaft nut, but you should search on saturnfans.com

Thanks, you were exactly right. Just got off the phone with the mechanic, that and the valve body.