i dont no if it will help,but i have a 78 2wd jimmy w/ 1.25 roters,plus my 85 c/10,& had a 77 h.half lb., now i just tore down 84 sb for parts & its got 1.00 what is differant then the others its manuel brakes & steering,6cyl.-3 on-the-tree maybe thats the key...roll low..drag hard ..toby