You can actually buy longer posts. I had to get one for my old bravada. Google "gm side posts". I pretty sure thats what your talking about and will need.
they have bolts in bolts at o'reilly and autozone the bigger bolt is same as stock goes in to the battery after you tighten it theres a smaller bolt thats screwed in the top of the bigger bolt which can be used for other + and - lugs.