Master cylinder "gasket" to firewall with integrated bellows seal retainer.

So yours has foam as well as what Dana is making? I'll have to chk 67 parts manual to see what's what for ours. But brakes work great, factory disc with a drum/drum reservoir.
Let me know what you find, 4spd. I've got body, chassis and parts manuals on disc but from what I've searched I can't find Master cylinder details for the A body. It shows a complete view for the Imperial and another for B and E bodies but all they show for the A's then is the pedal assy. Very strange unless I'm missing something. I heard yay's and nay's regarding needing a different master with the disc brakes switch but decided to change over just to be safe. Glad I did so far considering what I found upon removing the original.