66jack

I was cleaning out my shed and took down some numbers on some Differntials...
1. Is this a 63/64 differential?
Ring gear #3733908 which are 4:11 according to my parts book and shows this number to be for a 63/64.
the other stamps on the ring gear are 9:37.....(2-21?)....gm 5 65 1
AND on the case all i can make out is (CF 103) i cannot read the rest of the stamp...
2. Is this one a 65/67?
The other ring gear #3720089 which are 4:55 in the same book and all the other numbers on the ring gear are 9:11 gm 6 63....

I know these have not been touched since i bought them in 1976..

Also how can i make the stamps readable on the case, i've wire brushed them and cleaned them and still cannot make out the stampings???

Jack

66jack

bump

62corvette

The first one has 9:37---that means 9 tooth pinion, 37-tooth ring gear, = 4.11 ratio, as you had already gathered.
The second one probably has 9:41 rather than 9:11--that would correspond with the 4.55 ratio that the parts book indicates.
6 63 and 5 65 are June 1963 and May 1965 manufactured, respectively.

63 340HP

On the #1 case, the gears appear to be 4.11 (9:37), but the CF code leading the numbers on the bottom of the case reflect it held a 4:56 gear set from the factory. It may actually be stamped CE, the code for a 4.11 gear assembly, given how hard it is to read.

There is usually a number right after the CF or CE, like "CF5 10 3" for a 4.56 gear case assembled 5/10/1963.

Look for the housing casting date, located on the lower drivers side of the pinion housing. With the car assembled the casting date is blocked by the camber rod bracket (look above where the bracket bolts to the housing). The casting date is a letter and number code (my car has "L 8 2" for December 8 1962).

The pumpkins are worth the core value if you need a new gear set for your car. The correct case with the right gear, assembly, and date code may be more desirable for a collector, worth more to the right buyer, but I do not think an NCRS Judge is required to crawl under a car to read the code and deduct points if the codes are wrong (maybe one of the Judges will help?).

I have used magnaflux die and a black light to read weak code stamps, but usually thin paper over the area that is rubbed with a soft pencil will pick up faint stamps.

66jack

Thanks guys...thats more info for me to help detremine what they are...or are not...

jack