EXCELLENT POST BY "IBUILDTHEMBIG!" I would only add few things to it. When I did my "frame up restoration", I used a large crowbar to gently pry up the tub once everything was unbolted. This really helped to "unstick" those bushings off of the frame's body mounts. Also, I lifted my tub with an engine hoist hooked to the roll bar. I didn't have any big, burly jeepers to help me with the lift so I had to figure out how to do it with my engine hoist and my teenage daughters. We were able to do it but we had to think it through.
Some advice if you go this way...
(1) Make sure your jeep is where you want the tub to sit after it is removed. Once the tub was lifted off the frame, we rolled the chassis out from underneath. Do not try to move the engine hoist with the tub suspended. THIS IS AN ACCIDENT WAITING TO HAPPEN! Yeah, I learned the hard way.
(2) Have some big, burly guys to help you with this. When I lifted the tub off, it wouldn't totally clear the frame... it was only off by about two inches. Having some big guys around to help would have made this so much simpler.
(3) I used cynder blocks and 4x4s to rest my tub on. If you look at my "build" listed below in my signature, you will see how I had it set up. It may help you.
I hope this helps. Be careful and enjoy it. It was the first time I truly enjoyed working on my jeep was when I removed the tub. I was able to get to the frame and all the necessities without having crud drop into my eyes and such. It was very enjoyable after the tub was removed.
Take care,