KX 250 Seat Tab Bolt (Tank)

Are you planning on using the original tank ever again? Also, is there a plastic piece on there that the seat slides onto? What I would do is to try to order a new plastic piece, then go to the hardware store and get a bolt to fit the thread insert in the new tank. That way you can swap tanks back if the need ever arose. If the old tank is complete junk, carefully drill the head off the bolt that is in there now, remove the plastic piece that the seat latches to, and then go get a new bolt.