they're 1/4-20 shoulder screws. Not exactly sure the length or shoulder size but if you just get regular screws you can chance cracking the plastics so choose carefully...
grainger sells a tamper proof version. so as long as you have the right torx bits its no issue. it has all the dimensions of the shoulder if you want to try to find them somewhere else.
If anyone needs the Oem stainless shoulder bolts with washers I have :
6 dozen ready to go. $10 a dozen
3 sets of 20 without washers. $10 a set
3 sets of Black body panel bolts 6 short, 6 long with washers. $5
also the threads for where the seat bolts down, is that inserts in the frame rails or are they threads right in the frame?
if they are inserts, can i get a part number....and how to get them out!