Not much help with knowing stock length. If it`s not your dd, go ahead and drop it down then measure what you need for bolts. Can`t remember if all cab bolts were same length or not.
Idk man I just went down stairs and dug through the bolts bucket till I found one....almost certain it was a body mount bolt. It'd say they are all the same. The have a non threaded shank.......I'd get them that length but all thread. You should be good to go then.