96 safari, with 214,000 miles. runs like a top. no ticks or knocks in engine. As of right now, its making a hell of a grinding noise, similar to metal on metal brakes. but goes away when i put it into neutral, or when i hit a certain speed. Maybe when it shifts? out of first..
Does this sound like trans?

better check all your fluid'sin the axle and trans ,pull the drum's see if any thing is floating around loose . better check the rear axle mount's were the spring's mount to it they like to rust out and the axle will float around .