Do you mean the bolt that bolts the buckle onto the tranny tunnel? Is it rusted or broken?
Anyway, you may want to try a universal belt from
www.GotBelts.com or somewhere like that.
I ordered one from
www.GotBelts.com, with a 9-inch buckle, 110-inch overall length, and the hardware kit for an extra $6:
http://www.gotbelts.com/relapshwbuen.html
I have 2002 seats, and I'll probably bolt the buckle onto the seat.
I don't yet know if it will fit, though.
I'm currently using one I ordered from
www.AutoPartsWarehouse.com, which looks a lot like the GotBelts one. The AutoPartsWarehouse one fit, but the buckle fit only on the tranny tunnel, not on the seat, because the eyelet was too small for the seat bolt. However, the buckle is too long (14 inches), and it's upside down when installed on the tranny tunnel (the buckle cable has a weird bend near the eyelet, so it can only be installed one way), so I ordered the one from
www.GotBelts.com.
The GotBelts one has a buckle that looks like it'll probably fit on the seat, because the eyelet looks bigger on the 9-inch buckle, and it looks like it probably doesn't have the weird bend that my current one has (my current buckle resembles the 12-inch buckle at GotBelts). However, I have no idea whether the other parts will fit, although I'm guessing that they probably will.
I have no idea whether the safety (will it fail during a crash?) is as good as a Ford belt. But at least, the one I currently have, retracts nicely. I'm guessing that the new one will also retract nicely, because it's not a Ford belt.
By the way, if anyone knows of an aftermarket lap-and-shoulder belt (3-point?) that is known to be safe, I'd be interested in hearing about it. I couldn't find much info, regarding the safety of various aftermarket 3-point belts.