Violent bucking when letting off accelerator

Hello all. First post so please bear with me. First Jeep I have ever owned. And I'm absolutely hooked.
It's a 94 with 220k+ I6 Auto 4wd When driving down the highway I let off the accelerator to coast and it sounds like the world is gonna end. Violent bucking that sounds like it's coming from the rear driveline. It will also buck again when I reapply the accelerator. This thing has done amazing stuff off road that have left my friends jaws on the floor. Please help.

Motor mounts or tranny mounts.

I will take a look. Thank you.