Re: 96 Bronco - transmission shudder
Even the best-maintained slushbox will eventually wear out, so take it to a pro for diagnosis.
Regardless of what parts have been changed, the most likely causes of a clunk are 1) U-joints, 2) rear pinion nut, 3) frame noise, $ 4) normal slop in the t-case & rear diff. The engine/trans mounts are padded with rubber, so they don't usually make noise even when they're bad. They just allow the fan to hit the shroud. So always start by rechecking any recent work (or take it back to the shop & let them recheck their own work) and then examining the driveshaft.
To diagnose frame noise, click my black Bronco in my signature, scroll to the bottom of the list, & read the captions in the Frame Noise TSB album.