putting 231 back together, where do these bolts go?

so i have the normal case mounting bolts to bring the case together as one piece and i have two bolts w/ washers on them, the rest are all common, then one 10 mm 12 point bolt. i dont remember where this 10 mm bolt went i know it was on top but its very, very difficult to thread into the top-most hole. any advice or perhaps a pic?