Is there difference between MC for power vs manual?

gdizzle said

So is it possible that the M80266, that states for Rear Discs, does that mean I am missing the residual valve I should have since my rear is still drums??? I thought the M80266 was on the interchange list, but ??? When I type in that part in Rockauto, it brings up all the other Part numbers that I listed in my first post. Surely they are all the same, right? Also I have installed an adj proportioning valve to the rear, and I have it wide open and it still does not lock up.

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If a master cylinder states it is for rear disks, it will not have a rear residual valve. Which you do need to have if you still have rear drums- that could definitely contribute to the brakes being soft.

As far as the interchange goes, I don't know what to tell you. Sure, they should all be the same. But that depends on the person making the list, and changes to the parts by the manufacturer since the list was made. Meaning, there's no guarantee all those parts are actually identical.