Brakes

[orangeGMC]

How do I know if I have JB6 or JB7 brakes on my 78 K25 pickup? I have to replace my master cylinder and the Autozone guy doesn't know the difference. Also which would I use when I do my rear disc swap? Does anybody have some part numbers I could cross reference?

 

[orangeGMC]

Can anybody help me or give me a link to an old thread or something?

 

[83ZZ502_Jimmy]

Is the code on the glovebox door or similar? Sounds like a RPO code.

John

 

[77crewcab]

I had the same problem with mine. Check the size of the rear drum 13inch is JB7. As for the disc swap I dont have a clue.

 

[orangeGMC]

I don't have anything on my glovebox. Iam not even sure it is the original one.

 

[shane74]

You can find the code on a sticker on the glove box door.

For a new MC, use the JB7 code.

If you have anymore ?'s about a disc swap, feel free to pm me.

 

[divorced]

I couldn't find any codes in my glove box either. I brought the truck and vin number to the local Chevy stealership and they couldn't even tell me which it was. The parts store ordered both for me to compare and they looked identical with the exception of different color paint markings. I bought the JB7 master cylinder and it works fine with my rear discs.