Diff date code

[Mark G.]

I understand the diff stampings are not judged, but I'd like to get the correct one for my 69 L71. Bought it in 1977 and 43 years later, I get the original window sticker from the original owners daughter and my car came with a 4.11. I found one dated Jan 02, 69. Would this be too early for a July 24, 69 car? Thanks.
Mark

[Michael J.]

Re: Diff date code

I guess it depends on how much of a perfectionist you are. The NCRS guidelines for dated parts is within 6 months prior to build date. January 2. for a 24 July car is just outside the window, but not by much. If that is the closest you can do, it is not bad.

[Mark G.]

Re: Diff date code

Asking this because I don't know the answer: It is a 4.11 rear for a 427. Is that something GM would have made in a run of 4.11"s seeing as that wasn't a common ratio, stamped, and sat until needed? Or were they built then dated when the car was ordered? Also, how soon to the car build is to close for it to be correct?

[Patrick B.]

[Tim G.]

Re: Diff date code

Mark, I'd hold out for something a bit closer to the build date of your car. If it were a carb or starter, I'd say get it and upgrade if you find a more desirable date. A differential is a big project to install, so wait for one that really fits well. I had this dilemma with an original windshield and held out for a date with a good fit and it finally came along.

[Michael J.]

Re: Diff date code

A 4.11 rear is miserable to drive with. It feels like being stuck in 3rd.

Ha! To each his own, but I have a 4.56 in my '63 Z06, and it is a joy to drive, that ratio keeps that solid lifter, hi-rev, SHP engine in the power band most all the time when cruising. It's like a little rocket ship.

[Joe L.]

Re: Diff date code

Ha! To each his own, but I have a 4.56 in my '63 Z06, and it is a joy to drive, that ratio keeps that solid lifter, hi-rev, SHP engine in the power band most all the time when cruising. It's like a little rocket ship.

Michael------


Yes, as long as one is just cruising around town, I guess it would be OK. On a long road trip, forget it. Period. It would take all the pleasure out of the trip for me. Same thing happens with side exhaust.

[Michael J.]

Re: Diff date code

I fully agree Joe, it depends on how and where you drive them. I don't use my C2s for long distance interstate trips, I have a new one for that. But around town, in parades, at car shows, etc., the 4.56 is a great gear, also when starting on hills, as I have a lot where I live, those SHP engines low end torque is lacking for launch, the 4.56 makes it very drivable in that kind of terrain.

[James G.]

Re: Diff date code

I had a 4.56 in my 57 black fuel car. Drove it up all the back roads HWY 1 to BIG SUR and CARMEL one summer from San Juan Capistrano. GREAT trip that took time, and I was in love with my sweet wife. 1978 time

[James G.]

Re: Diff date code

LOOK at engine date. Differential date will by close to the same for correct date

[Mark G.]

Re: Diff date code

T0708LR July 8, 1969?