My '83 Master Cylinder won't match up with my later Prop Valve- std threads vs. metrics- I find out from here-Thank You.
Looking, I find 2 Master Cylinders for later rear disc cars.
Regular and Performance Package. I guess the PP is the 1LE.
My new brakes are C5 fronts & 11" rears- should I be getting the "Performance" Master Cylinder?

 

Yes that would seem best.

And the prop valve for that system as well... the 90-92 one. Should match the brakes themselves the best.

 

Thought the threads were the same thru 89, 90 up were different ones.
PP 1le master is just a standard disc/drum master.

 

Scratching my head, I checked part #s.
Seems you are both right.
Checking Raybestos, the master cylinder listed for the "Performance Package" for '88 is the ONLY master cylinder listed for the '90.
So, what was performance in '88 is std in '90.
Thanks for the input.

 

The Parts and Illustratipn Cat., 89-91 (and probably 92 as well), shows the same Cylinder, Brk Master GM 18014286. Earlier years show different masters for J50 and J65. GM, however, pretty much made them interchangeable. See the 10-Bolt FAQ should you wish to know more about that issue.

JamesC

 

10 bolt FAQ- now that's a cool thread....
Still scratching my head over trying to find adapters, so I can keep my front to back line for my rear brakes.