Hey all. Just got the Jeep out and hit some mud (small bits, nothing bogging it down) and at a stop sign, I put it into N (I have 5 speed manual) then pushed my lever forward to 2WD and I heard a knocking sound. It sounded like it was coming from the center of the back seat... any ideas? Maybe low fluid? Also, my 4WD Low won't engage... Ive been told its Vacuum... but thats hard to believe. Jeep is a 1984 2.5L I4 with 5Speed manny tranny. Dana 30 up front, 35 in rear.

Sorry if I didn't see this elsewhere...