Good grief, I feel your pain man, I really do. I have had not only the studs that hold the bracket down break, but also the internal seat fram break. They really aren't very sturdy being constructed of thin gauge stamped steel, with only spot welds to hold it together. It is likely that if it isn't a missing nut or bolt, that the holes attatching the seat to the bracket have cracked and let the seat seperate.
You can unbolt the seat from the frame (If you have gearwrenches this may be easier, a socket won't fit.) and have the busted bits rewelded. In my experience, if you can find some scrap iron for reinforcements and some nice big washers for the bolt holes, you can get a really sweet deal on welding if you pay cash and prepare everything beforehand. What I had to do, was strip the seat, measure and cut all my reinforcements (Hacksaw and a file will work for this, if you have the patience), then reinstall the whole thing. I drove down to a local autobody shop and talked to the guys there. Once they agreed to do it, I went out to the parking lot and disassembled the whole thing again.
*Zap, zap, burn* and it was done. $30 bucks later I was in the parking lot putting my seat back together.
Since you have the older style seats, the disassembly is a more complicated process, the newer ones come in two pieces (Seat and backrest) but I have done the same thing on both styles. If you would rather have someone else disassemble the seat, prepare yourself for a much bigger bill, without a cash discount possibility.
It sucks, I know, but if you can find someone to weld it up, awesome. Otherwise, just make sure your bracket is in good condition and buy aftermarket seats. Used seats are almost always in bad shape, and putting the passenger seat on your side doesn't really solve the problem long term.
Good luck man. I'll check back later to see if you have other questions.
