With OEM clamshell type motor mounts or with bushing in tube style? OEM mounts allow a lot more movement, especially with worn ones, and I could see that happening. I was going off the trans mount kit from the same company I got my motor mounts (I didn't order the crossmember).
https://davescustomsunlimited.com/universal-transmission-crossmember-kit/
"The universal kit mounts to the inside of the frame above the skid plate. It allows the skid plate to be removed without lowering the transmission and transfer case assembly.
This well-engineered kit is designed to eliminate the factory center transmission mount, which will be mounted solid to the supplied plate. Furthermore, the urethane bushings at the ends of the new crossmember will act as the new transmission mount. The factory design was very poorly designed. It acted like a tripod. The engine was mounted solidly with two mounts and the transmission with one mount, which in return, the transmission wants to torque MORE than the engine. This is why guys/gals tear up their transmission mounts or crack their adapter housing. With our well thought out, unique design, you now have FOUR engine and transmission mounts, which will allow everything to torque the same, furthermore, alleviating blown out transmission mounts and cracked adapter housings."
I may actually go with something like this from advance adapters, which goes with the tcase adapter kit I'm using, and acts as a partial spine to reinforce the mount. Still with a removable crossmember, but it could be hard mounted at the frame.
http://www.advanceadapters.com/products/716055--heavy-duty-transmission-mount/