need help determining GM codes for master cylinder
 

Hi folks,

Having a bit of a problem figuring out the correct master cylinder for the power brakes on the 77 c-10 4x2 short bed....was originally a 305 automatic with air,ps,pb...

It's been "worked on" alot before we got it and we found a bunch of rigged up stuff so I don't even know if the master cylinder on it is the right one....

It has the heavy duty suspension... as it has the big shackle mounts and big springs on the back. it is a 5 lug....

When I try and look up the part I'm asked what the GM codes are on the "Service Parts Identification" sticker.;

they ask if it is a JB1, JB3, JB5

I can't find it stamped anywhere...The glove box decal is gone...

How can I find out...

Thanks,

Greg

Re: need help determining GM codes for master cylinder
 

Are the front rotors 1" or 1.25" wide? If 1.25JB5, if 1" JB3.

Re: need help determining GM codes for master cylinder
 

My apologies for not posting back sooner, but the last 2 weeks of college just about killed this old fart......thank god it's over, the scenery was nice, but now it's back to work before the old lady kills me…

They are the 1.25 inch...so that makes it a JB5....

Thank you for posting back.

Greg