Trying to ID the brake system on my '89 Cheyenne. The SPID shows a J code of J50. Can this be considered the JB5 system? It's the only J code on the SPID. The vacuum booster is the larger unit. There is no F44 code, so I'm assuming the truck is the light duty variety. Anyway's, I need to improve the braking, as they flat-out Suck !! With LS powertrain, the truck is more lively and responsive, but the braking is just NO match for the added power. Thanks