Q's regarding cab mounts and ride height

[Evs-One]

So I have a 70 c-10, lowered 3/4 with Brothers springs and Doetsch Tech shocks. My drivers' side is sagging a little- my cab mounts are worn, so I ordered some urethane ones up the other day. Well, I can see how cab mounts being worn out will change ride height at the front, but it seems like in the rear, the drivers' side is also lower- but there is no mounts unde the bed that will sag...is there? I just want my truck to be even all the way around. And while I'm at it, the mounts are pretty straight forward? Support the cab, remove old bushing and slide new one in?? I have a bunch of questions that I know are somewhere on this board- but the search function isn't the greatest :P

Thanks fellas