I posted this first in the Tranny section wiht no answers. Though maybe I might get more response here.
1988 Bronco II v6 automatic park doesn't work. just like going into neutral. Tranny shifts and drives fine. So the question is does this require a complete teardown to fix or is there some other linkage issue that could cause this.

 

could it possibly be the parking pin/lug is sheered off?

 

I would disconnect the linkage at the tranny, and run it thru the gears to see if it is the tranny or the linkage.

 

Could be a linkage / gear selector / gear selector shaft issue with adjustments or bent things - or, you could have a broken park sprag in the transmission, which unfortunately I am unsure if the A4LD's parking sprag can be replaced without a rebuild. I agree with tommyleea, I would carefully separate the linkage from the transmission and check to ensure that it is either a linkage problem or a transmission problem.