THE MERCY-4X SIMPLY HAS LONGER QUARTER-PANELS. THE MERCY-4X IS A LONGER VERSION OF THE MERCY-4 BODY-KIT AND WITH THE MERCY-4X YOU WILL NEED TO STRETCH THE FIREBIRD 7.5" MAKING THE WHEELBASE 7.5" LONGER WHICH WILL MAKE THE QUARTER-PANEL SECTION WHICH IS LOCATED BETWEEN THE DOOR AND THE REAR WHEEL 7.5" LONGER. ALSO BECAUSE THE FIREBIRD'S MOTOR IS IN THE FRONT IT MAKES IT EASY TO STRETCH THE FIREBIRD BECAUSE THERE IS ONLY A FEW BRAKE LINES AND WIRE THAT YOU HAVE TO STRETCH AFTER YOU STRETCH THE FLOOR-PAN.
THE TWO VIDEOS BELOW EXPLAIN ABOUT THE MERCY-4X WHICH IS FOR A FIREBIRD THAT HAD BEEN STRETCHED 7.5" TO MAKE IT FIT THE MERCY-4X BODY-KIT. THIS VIDEO EXPLAINS HOW TO CUT THE TOP OFF THE FIREBIRD AND PREPARE IT TO BE MODIFIED TO FIT THE MERCY-4X.