Exterior Mirror Date Code

[Joel K.]

The mirror on the '68 I'm working on (supposedly original to the car) has the date code "8 DCA 6". From the archives and other sources I've been given to understand that C-3 mirror date codes should reflect either Donnelly Mirror (DMI) or Ajax Mirror (AX) as manufacturers. Anybody ever seen a "DCA" coded mirror?

[John H.]

Re: Exterior Mirror Date Code

I believe at some point Donnelly changed their name to "Donnelly Corporation America" after some merger or acquisition, and their code changed from "DMI" to "DCA". There was a thread on this several months ago.

[Joel K.]

Re: Exterior Mirror Date Code

I believe at some point Donnelly changed their name to "Donnelly Corporation America" after some merger or acquisition, and their code changed from "DMI" to "DCA". There was a thread on this several months ago.

Thanks, John. With respect to the dates, the code on my mirror would seem to reflect an August X6 manufacture date. However, to the best of my knowledge, the mirror is original to the car. Any evidence that the company might have used a "year-DCA-month" sequence?

[Michael B.]

Re: Exterior Mirror Date Code

I have a 8-DMI-8 on my 10-04-68 build date 69 Coupe.

[Chuck S.]

Re: Exterior Mirror Date Code

Thanks, John. With respect to the dates, the code on my mirror would seem to reflect an August X6 manufacture date. However, to the best of my knowledge, the mirror is original to the car. Any evidence that the company might have used a "year-DCA-month" sequence?

Since John indicated the successor company became Donnelly Corporation of America (DCA), and the fact that my July 70 car had an original 5-DMI-0 mirror, I think the obvious conclusion is that the mirror is not original to the car. It probably is an early service replacement manufactured in August 1976. Beyond the seventies, however, use of the last year digit becomes less reliable as a date code for any component.

The good news is that you still have an original GM mirror from the period into which a correctly dated glass can be installed. From Michael's experience, and from my own, it appears about two months before your build date would be a good date. I can't add any information on current sourcing of such mirror glasses or how well they judge, but Paragon once supplied dated mirror glass. There was an article by Terry McM in The Corvette Restorer a few decades back that detailed the procedure for mirror glass replacement.

[Michael W.]

Re: Exterior Mirror Date Code

I have two mirrors known to have been made in 1976 which still show DMI vs. DMA. These however have the long heads typical of a current at the time C3 style and not the short heads originally used on '68s.

Is it possible that the mirrors in question were made in '86?

[Chuck S.]

Re: Exterior Mirror Date Code

I have two mirrors known to have been made in 1976 which still show DMI vs. DMA. These however have the long heads typical of a current at the time C3 style and not the short heads originally used on '68s.

Is it possible that the mirrors in question were made in '86?

Mike, the short answer is I don't know the answer.

At some point, year date codes on parts seemed to have gone to two year digits or some other format to eliminate confusion, and most such dates I've seen were in the early 80s. I'm thinking a mid 80s date code using only the last year digit is unlikely that late, but BWDIK.

We don't know for sure whether the mirror in question is the long head or the short head, but since Joel said he believed it to be original, I assumed it was the correct short head. Someone that knows the background on service replacement mirror and the supercession would have to answer, but my belief is that once the long head mirror was in production, production of the short head mirror for service replacement would have stopped immediately or soon thereafter. The fact that you have DMI stamped, long head mirrors as late as 75/76 increases the mystery if Joel's mirror is, indeed, a short head mirror.

[Jack H.]

Re: Exterior Mirror Date Code

The issue might shed resolution if we knew when Paragon bought the tooling from Donnelly. I'd suspect that was when the DCA logo ceased production and the DMI logo returned...

Also, when Donnelly was actively supplying GM with parts, I'd expect the service folks to have been ordering BOTH the short head and long head versions side by side to meet customer demand...

[Tory S.]

Re: Exterior Mirror Date Code

My all original '75 conv. has the left mirror - large head - dated 2DMI5 for Feb. 75. So DMI was used in 1975.

Now the funny part, the dealer-installed optional right mirror was incorrectly installed as a small head, but dated 3DMI5 - March '75.

My car was built April 4th and delivered to me on April 15th, 1975.

Thoughts?

Tory