Bad transfer case mount?

I noticed that if i hit the gas a little hard off a dead stop i will feel a somewhat bad clicking in the rear, kinda like where the back seat floor panel is. kinda feels like bad shocks but i just got brand new ones. then if i brake hard enough i will feel it up front. and sometimes if i stop on a hill it will keep clicking even though im not moving. i looked at the crossmember it sits on and its a little bent from a rock i would guess, and the pad is almost non existent. the t case is floating like a half inch above the crossmember and the cross member is even bent upward. would getting a new mount fix everything? or do i gota get a new crossmember as well? i also get a vibration at around 45 and it gets pretty bad till about 60, then it goes away. 89' Cherokee Laredo, 4 dr 4.0 auto. 3 inch add a leaf and coils up front, rustys lower controll arms.

1) There isn't a "transfer case mount" - there is, however, a "transmission mount." It typically will transmit vibrations at all speeds when it's failing, tho.

2) You can check to make sure the transfer case mounting studs/nuts aren't coming loose - there are six of them (one or two up top may be difficult to reach. Unbolt the crossmember and lower the transfer case on a floor jack to get more room overhead if you need to. Detach the transfer case linkage and/or transmission shifter if required.)

3) You are likely losing the Cardan joints in your rear driveshaft. Check by gripping the driveshaft in one hand and the slip yoke/pinion yoke in the other, and twist in opposite directions (check both joints.) There should be no discernable movement. Alternative - drive to refresh your memory, then grease the joints (you can grease and test one at a time if you wish, but you should replace all of the joints in a shaft.) Drive again - if the vibrations are lessened, replace the Cardan joints.

4) While you're down there, look all around the driveshaft for a "clean spot" where a balance weight may have broken weldments and fallen off. If this happens, find a driveshaft shop and have the shaft rebalanced (or secure a replacement.)