Rear Caliper Seals & Dust Shields - Services (1) Rear JL8 Caliper w/ 1.32" Bore Diameter The 4-wheel disc brake upgrade (Corvette style 4-piston calipers for both front and rear) was offered on the 1968 Camaro as a "Heavy Duty Service" package sold through the parts counter at Chevrolet car dealers. In 1969, the 4-piston disc brakes could be ordered as a Regular Production Option (RPO) JL8 package on production vehicles. These high-end brakes were made available to support racing programs like the Sports Car Club of America® (SCCA), and Trans-Am® road racing series. This unique brake option is very rare and was only sold on about 200 production vehicles.