My 1993 Suburban rattles and vibrates terribly when in reverse (only after being driven a while)?

akclueless

We did just put on winter tires that were balanced a year ago and it does not have emergency break on.

What do you recommend I start looking at to figure out the problem?
We had transmission replaced a few years ago.
We also are losing power shifting into 2nd gear on hills (automatic).
It seems to only occur while in reverse.

akclueless

a mechanic friend thinks the transmission mount is bad/falling apart....any thoughts.