Perches: Rear Leaf spring 67-69 F (choose) This is a pair SET.This is a pair SET. On the diff housing of the rear on any 67, 68,69 Camaro or Firebird is the diff housing locating PERCH they are different for MONO Leaf or Multi leaf rear springs. LEFT IMAGE MONO.. RIGHT IMAGE MULTI They require precise professional welding to the housing, along with the change of saddles cushions, anchor plates , shock pins and U bolts etc.. which all are different when fitting single or multi leaf springs when changing over