Greetings, I've been out of the automotive service industry for a number of years, but I have now started working on my own vehicles again to teach my son and daughter about basic vehicle care.
I am finding that the automotive parts stores, online and in person, are asking for information I am not easily finding on my vehicle. I have a 2008 GMC Sierra 1500 SLT Z71 4X4 V8 - 5.3L vin 3 325ci Flex Fuel with a factory electric tow module (tow package I think). Just purchased truck used.
The part stores are needing to know if I have a: Vacuum Boost System or a 7700 Lb. Vacuum Power Brake with JD9 Brake System with JL4 Suspension.
Looking at the brake and master cylinder it is a very simple looking set up, metal vacuum boost (not really large) and a small master cylinder with bigger plastic bowl. Nothing to indicate 7700, JD9, or JL4.
Maybe terms just indicate a "better quality" part and not a totally different, will not fit part.
Or do we just hold up parts and compare shapes?
Call a GMC parts department and ask them where the option code tag is located on your truck. There you'll see if you have JD9, or JL4.