Scott and others are right on with the size of the bolt heads.
be sure to threadlock the bolts in when you install the new shaft (if someone mentioned that already, my bad). some guys use their leg against the wrench to loosen the bolts. i tell ya, those stupid 12 point 12 mm bolt heads scare me - if one has a slightly loose socket, he/she can be SOL real quick. LOL.
on foxes, the alum DS is a half inch bigger than the stocker (per Mav, over in 5.0 tech. he just measured both of his. we have clearance issues too, sometimes).
im about positive you use the same alum DS as a fox does, but dont know if your stock DS is more beefed up or something (larger diameter) than fox stock DS's are.
(sorry for the fox references - im lookin to buy a 94 -95, so im haunting you guys).