Check out Fabtech lifts... www.fabtechmotorsports.com, they're the leading technology for lifting Chevy's.. and we've talked about this truck how many times now?? lol.. Im pretty sure my friends truck is only on a 6" and he's fitting 36's. Also, check out www.pavementsucks.com and ask their opinion on this, the guys there know more about this kinda stuff than most people here