I B RAKES 4 589 T127 1979 83 BRAKE CHART The following charts list the 1 9 7963 Light Duty Truck Brake Systems These charts must be used to determine the exact brake system on e particular vehicle To determine the correct brake system the following information must be known 1 Gros Vehicle Weight lGvWl This is given an the identification tag located on the drlver slde door pillar or on Step Vans attached to the lnslde face of the dash and toe panel Z Model Numhen 7 l LD Power Brakes IRPO J55l This is an option avaliable on most vehicles when trucks are eouwped with this optlan the bralte system may be upgraded to the next higher rating Example from 53 to 55 Trucks equmped wlth this option can be identihed hy checking the Service Parts identification Sticlren EXAMPLE lf the mick had a C10 and 5400 GVW lt would be equipped with JB bralre system lf the truck was equhoped with J55 l LD Brakes it would have the JB5 brake system 197931 LIGHT TRUCK BRAKE SYSTEMS ncmn nun nnuwnoron rowen aoccrsn JB3 II 80 x 1 28 9 5 Single Dlaphragm JB5 II 8B x 1 28 1I 18 x 2 75 9 5 x 8 Diamaur Tandem Dlaphragm 11 15 x 2 75 9 5 x 8 Diameur Tandem Diaphragm JB7 9 5 x 8 Dlametar Tandem Dianhragm t M M v Jn 11 eo x 1 zs uyarosom M we tus x me nyam sam R M v WAIIEHOUSING AND DISTRIBUTION DIVISION OF GENERAL MOTORS OORPORATION LT TRUCK 52A REV 1 84 4 1 s 4 000 GROUP