Ring and Pinion Numbers

[tim69camaro]

Do ring and pinion gears have date codes? The numbers off each are below. Some are obvious like the 14 43 for a 3.07:1 ratio and some appear to be part numbers. Some of the others I am not certain. If I were to guess the 11 68 is November 1968 for the ring and 10 68 is October 1968 for the pinion. If these are dates could this be a matched set if the gears were not made on the same date?

Ring Gear 1 GM 3862691 14 43 11 68 10-2
Pinion 2 10 68 GM 3853003 14 43

[rich69rs]

I believe that you are correct as far as the 68 that you found on the ring gear.

As an example, my original, numbers matching, '66 Chevelle, has the following information stamped on the OD of the ring gear:

GM  3790628   1137      65

GM  3790628  is the Ring Gear P/N, Stamped on OD of Gear
1137 is the ratio; Ring Gear  37 teeth, Pinion Gear 11 Teeth = 3.36:1 rear end
65 is the year of Manufacture (1965)

As in your example where 68 = 1968; on the above 65 = 1965

I have the protect-o-plate on this car and the rear end was assembled in Oct 27, 1965 although my Chevelle was built in Flint in mid March 1966.  One of those fiew examples previously documented in this forum where a rear end, for whatever reason, was not used immediately after assembly.

[Jerry@CHP]

Have set up more rears than I care to think about.  Just about all of the factory gear sets that I've seen over the past 35+ years always have the date on them (month and year).  Sometimes they are a month apart even in a matched set.  I suspect this was due to production control and how Eaton scheduled running the gear sets in on the Gleason gear machine.  Maybe John Z can add more to this.

Jerry

[tim69camaro]

Thanks you for the information Richard and Jerry. This is helpful.