Exactly what size drum brakes does my car have?

You should double check by taking you wheel off and the dia. is stamped on the drum. It is likely 9 inch but I have ran accross more than one slant 6 with 10 inch. I have one right now. Have you checked local prices? I gave under $14.00 per axle for 10 inch shoes for a 1969 Dart fairly recently.