cab mount replacements

[shelby987]

I am still in the market for a 67-72 chevy/gmc (for those of you who read my 351 v6 thread). I have come across another truck in my area, its a 72 3/4ton 4x4, but it needs new cab mounts (according to the guy selling it, havent had a chance to check the truck out for myself just yet.).

The claim is that aside from the mounts, the truck is fairly clean. My question is this, how hard are the cab mounts to replace, and second....(currently no garage at my disposal), what would the likely charge be to have said cab mounts replaced at a shop?

Would it be a safe assumption to make, that if the mounts are shot, the floors likely are too, or is it possible for one to rust, while the other stays in decent shape?
Thanks,
p.s. located in S.E. michigan if that makes any difference.