vibration coming from front end while in reverse

hello all,
as stated above i have a loud vibration/grinding noise coming from the frontend area when i go into reverse at about 1.25-1.75 rpms. this started after i got back from a recent trail (Brewer Lake trail in Fresno County). my set up is a 00 xj classic, RE 3.5, stock dana 30, C 8.25, TC 242 with 1" drop, no sye or cv shaft. so what is my problem?

check the motor mounts

ok, so what will i be looking for?

Excess movement indicating a torn mount or a broken bolt

i noticed that the it sounds like the vibe and grind is coming from my front axle.