Hank,
I have this set of NOS ring and pinion gears available for purchase. The ratio is 3.54 to 1. I had another set just like these swapped into my 49 Dodge Coronet that came from the factory with 4.11 to 1.
Before I found these sets of ring and pinions I wanted to be able to go faster with my 52 1/2 to so I looked locally for a better ratio and found that a complete rear end would work in my truck with some modifications of the spring perches and drive shaft. My truck now has a 66 T Bird rear end with 3.0 to 1 ration in it.