Replacing Master Cylinder

Does anyone know what is the bore size of the OEM master cylinder on a 1970 Dart Swinger with front disc brakes? i believe the front disc brakes are a modification because the existing master cylinder compartments are the same size.
Brad's article that Oldmanmopar linked above is a great reference.

Here's the catch. Those disk/drum master cylinders are now harder to find. Kanter Autoparts has them, or did a few years ago.
For 1970 with k-H fixed calipers up front, 10.75 rear drums, Chrysler p/n 2808 600, casting will be 2225541, 1" bore.
You may be able to still buy a replacement (old stock) from Kanter Auto parts. Look on ebay with the part number and then the casting number if that fails. IIRC the username for Kanter is oldcarparts.

For 1971-2, the master cylinder was p/n 9461178, casting 3461187. It has a slightly larger bore, 1 1/32" diameter.

The big aftermarket companies like A1 Cardone just cheat.
They take a drum brake master cylinder and remove the residual valve from the rear port (front brakes).

When you open the box for a disk/drum master cylinder and find a master that looks like this, that's what they've done.
img_1120-png.png

It will still work pretty much the same. You definately want to check the fluid level more frequently since there less in the resevoir to compensate for the pistons moving out with pad wear.