Mason and Taylor were the last of the old Chicago distributors.
Through the years they bought out the others such as Ryan (Slant S mold) and Hunt (Chain mold).

I have Mason records that says they used Ryan blanks. There are Taylor records that says Hunt chain blanks.

There are both companies records that say there was interaction with O'Neil. I have seen records that say they used O'Neil dies for blanks.

There are Taylors records on 7 different molds. They usedup stock from the companies they bought out. Same for Mason.