Disc brake master cylinder

That picture is a DRUM brake master cylinder! That master cylinder is NOT a disc brake master cylinder! I've seen quite a few times in the past where people have gotten the wrong master from the parts store, when they go back and have the parts guy dig a little deeper they usually find the right one. There aren't to many disc brake master cylinders available for the 67-72 A bodies. The ones for 73-76 are readily available in both manual and power.