Difference in 850 vs 1000 frame/body, lift types?

I’m asking to find out what the difference is between the 850 and 1000 frame and body. I’m finally gonna get around to lifting my 1000 between now and spring. I was looking at different lifts and have been told that the frames are the same but the rear body/cab is made different so the rear lifts from one manufacture won’t work like another due to how it mounts. Didn’t make sense to me either.

I’m still not sure on what lift. I know you pay for what you get but I’m not getting robbed to do this, and for every person who says their lift from XYZ company went on great and works great, there are that many more people who say theirs didn’t fit or didn’t work as promised. So any honest input would be appreciated.