Vic, they are 1/2"-13 bolts top and bottom. I used grade 8. bottom ones I got 1/2"-13 by 4 1/2" long. I think i got 1/2"-13 by 1" long for the top. I also had to flatten the lower cups, and when I did it knocked the welded square nuts loose, so I used flats, locks, and nuts instead. give me a shout if you have any more questions.
joe
hey Jeff, it is a 3/4" head and nut. I will remember that for awhile. when I got replacement bolts they didn't have 4 1/2", and 4" were too short, so i got 5"...turned out too long so used the 5" with extra washers just to get it on the road, then I got the 4 1/2" later and replaced them this last weekend, quick easy job, right. got the driver's swapped, was just finishing the passenger's side when the 1/2" ratchet and 3/4" socket slipped off and I hit myself in the head, blood everywhere, freaked out the family. not to mention anti-seize embedded in the sore.
here is a pic after it has healed for a week
perfect socket shaped dent
oh, and......never-mind the receding hairline