1966 Differential Cover Dates. Post what you have!

[Mike B.]

Good Afternoon Guys,

I've scoured the archives for a definitive answer as to whether or not 1966 differential covers #3871375 were all dated? Most all of the threads I found were about 15-20 years old. None were written strictly about the '66. Most fell into the '65-'70 range. And I found far too many "IMHOs" there.

The current '66 Judging Guide states "The cover casting date is located on the right side flange just above the drain plug. These are not typically judged."

The reason I'm starting this thread is that some of my friends who own '66 Vettes have dates on their covers while some do not. I'm referring only to those who feel their covers are original to their cars. Another reason I'm starting this is because Bubba swapped my original HD differential years ago for another one dated from the early '70s. So I'm shopping for one that would have all the correct earmarks for an early December built '66 L36.

Most likely the answer is "Some do, some don't." But I'm very curious if there's a transition date range when this occurred? The only way that we might know is to have a number of you out there report what you see on what you believe to be your ORIGINAL 1966 cover. Both standard differentials or heavy duty. No matter. Not an exact science I know but it would surely add to 1966 archived information.

Thanks Everyone,
Mike

The following example cover photos are all of 1966 L36 HD differentials:

1. November 5th '65 built car with September 16th dated cover
2. November 9th '65 built car with September 16th dated cover
3. December 7th '65 built car with undated cover

Nov 5th built '66 L36 with Sep 16th dated cover (I-16-5).jpgNov 9th built '66 L36 with Sep 16th dated cover (I-16-5).jpgDec 7th built '66 L36 with undated cover.jpg

[Wayne G.]

[Gary B.]

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi Gary,

The data listed there in Nolands book only shows rear axle assembly date codes. I wish that there were examples of rear cover dates. I've stumbled on archived posts of yours from 20 years ago on the subject of this thread. Very informative. I'm hoping that we can compile a good list of '66 only data here of when rear cover dates appear. From what I've read in all previous threads it seems dates appear on the earlier '66 cover plates. Don't know the months of heavy usage. I'm hearing cover plate date codes are scarce on later built '66 models?

Mike

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi Wayne,

Good to hear from you. It will be excellent to see what your L72 posi cover reveals. That's a very special car you've got there and thanks again for sharing photos of her with me way back when? Since Gary poked me with Nolands book I checked out all of the survey data again that you'd provided Noland on your car. I especially enjoy the detailed paragraph that he wrote at the end of page 39.

Looking forward to data from a December built car right after mine. A photo would be great if possible! No matter if your cover is dated or not.

Thanks, Mike

[Gary B.]

Re: 1966 Differential Cover Dates. Post what you have!

Mike,

I’ll look at that area on my cover to see if there is a date…

Later… Just checked and there is no sign of a date on the cover for my July build date car.

Gary

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Thanks for the reply Gary! This is what we need. Hopefully we'll get a good sampling throughout each '66 production month.

[Wayne G.]

no date casting numbers.

[E S.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi- This is L72 ser.# 3795- Built Oct 22-65- Very original unrestored car- Very little has been changed since new- sorry for the poor picture quality-
E.J.

[E S.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi- Can't seem to get pics. to post, but L72 ser.#3795 Diff. cover is dated-Looks like I165-
I will try to post a picture again
E.J.

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi Wayne,

Thanks for rescuing this thread and moving it back up to the 1st page! Check out my buddy Ric's '66 L36 posi cover photo in post #1 by me. His car's build date is December 7th, 1965. Just a day or so earlier than your L72. His has no date on the cover either. So there's a bit of a trend goin' on.

Good to hear from you,
Mike

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Hi E J,

Check out the very 1st post to this thread. The top two photos that show dated covers are both from November 1965 built L36 cars. And both of them are very early VIN 5000 range. And BOTH are dated just as yours is -I165 - September 16th dated covers. There's another bit of a trend goin' on there too!

Mike

[E S.]

Re: 1966 Differential Cover Dates. Post what you have!

1.jpg2.jpg3.jpgMike- Finally got pics. to post-E.J.

[Mike B.]

Re: 1966 Differential Cover Dates. Post what you have!

Awesome car E J,

425 HP Nassau Blue coupe with white/blue interior. And she's a 4.11 stump puller too! Yep, September 16th dated cover.

Mike

[E S.]

Re: 1966 Differential Cover Dates. Post what you have!

Mike- yes-could be a trend! I would be interested in some of the dates on those other early cars.
My car has a 942 block (gusseted like a 65 425 HP 396)- and machined 10/19 65
Trans dated 10/18 65
Rear End 10/19 65
Car produced 10/22 65 (only 3 days!!)
Some other dates on this car: alternator 5F2
Starter 5K14
Carb. 593
Car still has it's born with P48's