that sounds like the rumble seat. It should also have a hole on the left side for a knob and rod which helps to secure/release the folding backrest. That style of seat is pretty old. Not sure where you might get parts. I had one and was unable to get parts even from Corbin. Bear in mind that if you do much two up riding, that folding mechanism reduces the passenger seat by 4 inches which gets uncomfortable really fast. Good luck with it
+1. My wife loves our Rumble (her Rumble?) but then she's "petite". If my son is on the back at 6 feet tall and 180lb, my man bits are pressed way up the gas tank