C3 Pinion Gear

[Don A.]

My 1969 BB differential was recently redone so I asked the mechanic to record all numbers and codes on the internals.The pinion gear number is 885942 GM 11 10/68 11:37. Does anyone know if the part number is correct and what GM 11 represents? Thanks.

[Craig S.]

Re: C3 Pinion Gear

Don - from my 1969 vintage Corvette GM parts book, the 3.36 ratio Ring and Pinion is P/N 3961423 (both the ring and pinion parts together as a unit). The note also indicates the the set is comprised of ring gear P/N 3735390, and the pinion is P/N 3885942. I would say he missed the 3 on your pinion, but you have the original parts here given the 10/68 date, as long as your care was assembled after that date within reason. The GM 11 probably has to to with the Warren Gear factory identification numbering suystem, but someone else will correct me if that is wrong...Craig

[John M.]

Re: C3 Pinion Gear

Don, Craig,
The 11:37 is the ratio, 3.36
John

[Craig S.]

Re: C3 Pinion Gear

John - in Don's original post, he has "885942 GM 11 10/68 11:37". I realize the last 11:37 is indeed the 3.36 ratio, but the "GM 11" in the front is a different 11 which I believe Don was inquiring about...and I still think this one relates to the GM gear plant ID marking system...Craig

[John M.]

Re: C3 Pinion Gear

Thanks Craig, I'm with you now. I just had one of these apart and should have taken a picture. I've been taking a lot of shots with a digital camera and storing them for later review. (helps a bad memory)
John

[Craig S.]

Re: C3 Pinion Gear

John - I have found this varies a bunch over the years, I have 3 corvette rear ends apart at the moment....a 66 BB 4.11 FB code, my 67's 3.55 SB, and a set of 4.11's (GM mfg) from 1980 through the parts system I am building up in a carrier. The later set is marked on the ring, not the pinion like the earlier gears, but is a GM gearset....Craig