Hey, shot in the dark here.

Replacing the brake lines on my 2005 cavalier, front to back. As far as I knew all of the fittings were M10 with bubble flares.

Got all the new lines run, and have a big problem.

The ports on the Brake proportioning valve have 2 fittings that are m10, and 2 that look like they are m12 with a much different thread pitch.

Now, is that how these come stock? Like if I bought a new part (ACDelco 22703518) would all 4 outs be the M10 fittings that are used everywhere else?

The car is old, so maybe at some point someone drilled those out to a bigger size? Or is that just stock?

Any help appreciated!

Hi Dan,

The fittings are different from the factory.
The reason is that this is a dual circuit brake system, and they do not want you to mix up accidentally the paring of the brakes when you renew the lines.
If I am correct the individual brakes are connected in X-pattern, LF to RR and RF to LR.
But do not take my word for it, the pairing, if it is straight or X-pattern, depends on the scrub radius of the front suspension!

Good luck, Peter