New master cylinder, brake pedal on floor next morning??

I believe that tear dropped piece of sheet metal is for shipping purposes only. I'd bet that many have been put together wrong with just that tab. There should be a plate on the back of the master with a boot on the back of it (which is why there are two holes). Mine got bent up when pulling up on the pedal to get the push rod out (stuck retaining o ring). Made a new one out of 1/8 aluminum and some 1/4-20 bolts. I wonder how many of these were put back together with just that tear drop. Scary thinking just that little tab holding it it. Power brake MC should have a snap ring holding in the piston. Lots have been done to these vehicles over the years with people of various levels of experience working on them and how we find them doesn't always mean it is right.