My '65 Valiant Signet V-8 currently has 10 inch front drums and 9 inch rear drums. A previous owner swapped in the current 7 1/4 inch rear end from a '74 Dodge. I was wondering what my vehicle originally must have had factory installed for rear drums 9 or 10 inch? And then the question in the thread title: Did drum diameter not match front/rear on some factory vehicles? Thank you.