Hello yall I am currently trying to figure out what my rear end ratio is in my 1967 Chevrolet Caprice. It is a 396 car and has a 12 bolt open rear end in it. I have referred to the charts online and attempted to match numbers/letters to find what ratio it is but nothing seems to match as mine reads FA 10 L. I really do not want to take off the back plate and start counting teeth. I need to know what this is as I am looking at installing a gear vendor into my Turbo 400 for an overdrive. I attached some picture of what I am talking about. Thank you for your help!

 

Easy way is to mark the tire and drive-line with chalk or something and spin the wheel watching the drive-line. That's a nice clean underside, BTW.

With a 396 Motor I would count on it being 3.07, 3.31, 3.73, 4.10, 4.56 and 4.88. That was a motor made for speed, not gas-mileage.