1994 GMC G3500 Engine: GAS; with AP Stamped on Booster; with Brake Code JB7; GM Brake Codes are on the "Service Parts Identification" Sticker; with Single Rear Wheels (SRW); without Master Cylinder;. 1995 GMC G3500 Engine: CNG; with Brake Code JB7; GM Brake Codes are on the "Service Parts Identification" Sticker; with Single Rear Wheels (SRW); without Master Cylinder;.
