I have a 67 Camaro, originally a six cylinder, now with a 327 high revving engine... made for running above 3-4000 rpm, and the 8.2 inch 10 bolt I have seems to have a gearing around 2.73 or 3.08... it makes driving it in town not a lot of fun... but it does not have a code in the usual plce on the right side of the housing on the axle. On the BACK of the differential up on top on the passengers side looking rearward is the number:

3894859

Does anyone know what this means or a good directory to look it up... There is another marking, looks like GM? on the left top of the case looking forward.

Check out the Camaro Research Groups page on First Gen rearends:
http://www.camaros.org/numbers.shtml#RearAxleNumbers

I believe that casting number - 3894859 - was also used on other cars of the era, but I could be wrong (again).

Since it sounds like all you want to know is the ratio, jack it up and spin the rear and count......

Joe... thanks... found it.

Also, Kurt... YOURE RIGHT! LOL.