68 corvette rear axle .. need help

[Dale & Abigail Patches]

While checking out our new "68" I found some number on the rear axle housing and need a little help understanding them

STAMPED on the underside 2 AV 12 16 67 W
On the rear cover "casting numbers" B284

On the transmission in casting 3834685 could be 3884685 (hard to read)

any help is greatly appreciated

[Joe L.]

Re: 68 corvette rear axle .. need help

Dale and Abigail-----

The "AV" rear axle code for 1968 denotes a 3.08:1 positraction axle used with 427 cid engines. Your rear axle assembly was manufactured at the Chevrolet Gear and Axle plant in Warren, MI on December 16, 1967 which would be correct for about a late December, 1967 or January, 1968 built 1968 model year Corvette.

The number that you mentioned which was taken from the differential cover is a date code and denotes a casting poured on February 28, 1964 or February 28, 1974. So, it's likely a cover used to replace the original cover at some point in the car's life.

3884685 is the casting number of the side cover used on 1966 through 1968 Muncie transmissions.

[Mike Baker]

Re: 68 corvette rear axle .. need help

Here's the way I interpret them. I'm sure I'll be corrected if I'm wrong.

2= Second Shift
AV = 3.08 Positraction (not heavy duty)
12 16 67 = Date
W = Warren Mi (assembly plant)

3884685 = casting number for the transmission side cover. (used on 66,67 and 68 Muncie 4 speeds)

Hope this helps

[Dale & Abigail Patches]

Re: 68 corvette rear axle .. need help

Thanks for the information ... in going back and looking at the build date of the car (May 15, 68) I am not sure that this is the orginal rear ..is there any way to verify that it is? OR what is the acceptable time frame difference between build date and axle assembly date?
The information that I removed from the rear axle was stamped along the flat surface which is facing the road surface .. is that the correct location?

[Joe L.]

Re: 68 corvette rear axle .. need help

Dale and Abigail-------

The location in which you have found the differential stampings is the usual location for them and the only location that I have ever seen them.

With respect to the difference between the differential date code and you car's build date, it is within the 6 month "window" which is allowable for NCRS and NCCB judging standards. However, in actual practice there was rarely a 5 month time lapse between the manufacture date of the differential and the build date of the car it was originally installed in. But, it could happen and NCRS and NCCB judging standards allow for it. So, while the differential unit may or may not be original to your car, it is within the acceptable date period for judging purposes.

Just for the heck of it, you might want to check the casting date of the differential carrier case to see if it's consistent with the stamped date code. This date code will be found on the elft side of the case, just above the strut arm bracket. It will be of the same general configuration as the cover date code which you earlier mentioned.

[Terry M.]

Differential judging *TL*

Since in both NCRS and NCCB judging cars are usually judged while on the ground, the differential stamp is usually not an issue. The only exception to the on the ground judging is NCRS Bowtie judging, a component of which is done with the car elevated to check among other items the differential and transmission.
Not withstanding these limitations, many of us want the assurance that these items are the parts originally installed on the car when it was manufactured.