No drain plug on the '55-'62s, just the filler. It'sa slo definetly not a Spicer, those have integral housing instead of the 3rd member like this one.
Ratios will be one of 3 choices, std 3.90, or the 2 options, 3.38 and 4.10.
You may have to look closely to find the numbers, they usually aren't stamped very deep, and can get lost under a coat of paint.
