Hello, what are strut/radius and what is the trac bar? I'm a rookie Bronco owner.

The strut/radius bushings are for the radius arms, one arm on each side of the front end and Bronco. These go on the end at the frame brackets, under the doors. The trac bar is the long bar at the front end, going side to side, from the driver side frame bracket, to the passenger side axle bracket.