They look STUD piloted to me with the flare on the nut to fit into the bevel tapered part of the wheel. If you can get a picture of the rear wheel and the stud has a square end it is definitely STUD piloted.When changing the rear wheels, that is a 3 piece stud.. The outer nut holds on the outer wheel then the square headed stud holds on the inner wheel threaded to a stud sticking out of the brake drum.. If the square headed stud breaks you then have to use a pipe wrench and cheater pipe to get it off.. If the square headed stud come off with the outer wheel you then have to hold the outer nut with a socket and turn the square headed stud thru the nut..
Are you totally confused yet???????? Also look out for left handed threads on the drivers side.. Should be an "L" stamped into the stud???
Be sure to use plenty of rust blaster and let it set for a while before trying to take the wheels off.
Diamond T and Brockway Collector