How to "ID" 70-72 Buick & 71-72 Oldsmobile
A-Body Sport Mirrors

by Duane Heckman

 

 

Sport Mirrors are one of the most popular options guys like to add when redoing their vehicles. They not only look nice, but with good examples of standard chrome mirrors getting more expensive and harder to find, they are gaining popularity.

You can find Sport Mirrors for sale all over the place, however the main problem is making sure you buy the correct ones. These mirrors were optional on almost every GM body style from the early 70's thru to at least the 90's, and the differences between many of them are not readily apparent. Right mirror image is a little grainy.

One of the reasons for the mirror differences had to do with the outer door skins. When installed properly the tops of the mirrors are parallel to the ground. (See the above pictures.) To accomplish this GM needed to take into account the differences in door skin angles for the various models. They did this in one of two ways:


1. 	They left the mirror housings the same, and changed only the mounting gaskets or
2. 	They changed the bottom housing that mounts to the door skins.

Then, to further add to the number of variables, as new models were introduced GM often changed the mirror designs. Normally this would not create an identification problem, but many of these changes were so slight that unless you have the mirrors next to each other you cannot see the differences.

The result is that people have trouble telling the mirrors apart, and are constantly selling mirrors for the wrong applications. Often this "mistake" is not discovered until the mirrors are repainted and installed on the car. Then the owner notices the tops of the mirrors are "cocked" inwards towards the center of the car, and they look stupid. At this point I usually get a phone call from the "Buick guys", as I am the guy that sells the "Buick style" mirror gaskets, and often have to explain that they purchased the wrong mirrors and need to keep looking for the right ones. (This is definitely not the way to make friends.)

The above scenario is becoming so common that I decided it was time to write this article to help everyone avoid this problem. To do this I took information from mirrors that were known to be correct and started looking at the piles of "parts" mirrors that I had in my inventory. While doing this I found at least 3 different mirrors (different casting numbers) that could easily be mistaken for the correct early mirrors and discovered that GM had also changed the mirror glass assemblies slightly. I even tried to install these "later" mirror glass assemblies into the earlier housings and discovered they were larger and would not fit correctly. Therefore, for identification purposes, I will also include the glass date code information to help ID the correct assemblies.

Identifying the Correct Mirrors

The first thing to note is the Sport Mirrors for both 70-72 Buick & 71-72 Oldsmobile A-bodies are identical in every way, with the exception of the mounting gaskets. The Buicks use a wedge shaped gasket (pictured above) while the Olds use a flat one with a thin raised lip at the outer edge. This allows the Olds mirrors to mount "flush" to the door skins, while the Buick mirrors require a beveled gasket to "shim" the mirrors so they sit correctly.

Another thing to note are the numbers that are cast into the housings. These casting numbers identify each piece of the assembly. On the upper housings the numbers are located behind the mirror, so if you tilt the mirror to one side both the number and date code can be seen easily. The numbers on the bases are located on the top of the part, where they attach to the upper housing. To check these numbers you need to take the mirrors apart to view them. Also, the numbers on the right hand bases are extremely hard to read (Cast very lightly); therefore it might be necessary to look at both the left and right bases before determining if they are correct.

The upper housings also have a variety of "Date Code Clock" cast into them. These codes have the last digit of the production year placed within a circle, with 12 spokes radiating out from it. Each spoke designates a month, with the longest spoke being January. Often a series of raised dots are used to indicate the month of manufacture, although in this case a single dot is used. Regardless of the number of dots, the last month with a raised dot will be the month of manufacture. In our case (See below pictures) the dot is placed at the end of the 4th spoke, therefore the casting dates for both these housings are April of 1972.

Here are pictures of the left & right upper mirror housing casting numbers and date code clocks.

Here are pictures of the left mirror base, including a close-up of the casting number.

 

The mirror glass is also date coded on Sport Mirrors. The code is etched at the top of the glass and lists the number of the month first, then the manufacturers logo, and finally the last digit of the production year. The below example of "2-DMI-2" would decode as February of 1972.

Summary

Listed below is the information needed to identify the correct mirrors for both 70-72 Buick & 71-72 Oldsmobile A-bodies.

 

Upper Housing


Casting Number 29853 (Left), 29843 (Right) (Numbers are located behind the mirror.)
Date Codes Anywhere from the middle of the 70-model year until the end of the 72-model year. (The date code clock is located next to the casting number.)

 

Lower Housing


Casting Number 29855 (Left), 29845 (Right) (Numbers are located on the top of the part, where they attach to the upper housing.)
Date Codes (None)

 

Mirror Glass Assemblies


Casting Number 29854 (Left), 29844 (Right) (Numbers are located on the black plastic backing assembly, on the backside of the mirror.)
Date Codes Anywhere from the middle of the 70-model year until the end of the 72-model year. (Date codes are etched into the glass at the top of the mirror.)