I just read a grip of posts regarding vibrations and still need some advice.
My story: While driving at about 50 mph in 4th my crawl box needle bearing seized which brought my tires to a dead stop and caused me to slide at least 50 ft. What I found was that the needle bearing on the coupler was seized and 5 of my ring gear teeth were torn off.
.............., had a shop install a new set of 5.29 gears and had them reuse my solid spacer(which are still being broken in).
when you installed your tcases did you dump 1 qt of lube into the front case shifter hole??
if not thats why your needle bearing locked up
.............. and were pro installed i wouldn't worry about that being the problem. it most likely is from the trans, clutch assembly or one of your t-cases. i hope that may help you. 
being installed by a "local shop" does NOT = a professional installation, there's a "offroad shop" near me that does gear installs for customers, i recently found out they dont have a bearing press and never have, they just "eyeball" the pinion and install what looks good
so what im saying is, CHECK YOUR PINION
make sure its not sloppy, also make sure your drive shaft is in phase, the bouncing you discribes sounds like a busted u joint or a badly out of phase shaft
