This information is culled from the various sources I have run into (factory manuals, parts books, interchange manuals, etc.) and is provided as a service to those people interested in working on, understanding, and restoring 1958 Buicks. I originally compiled this in working on my own vehicle and in helping others better understand their vehicles. I have provided it here in the hope that it could help some other folks. This information is provided as-is and may not be entirely correct. If you find an error in here, feel free to let me know.
The cowl tag specifies the most important information about your car - the exact model, body style, body number, the trim and paint codes, as well as some accessory information. It is located on the engine side of the firewall just above the drivers side valve cover. This tag is installed "sideways" and is easiest to read this tag when leaning into the engine compartment from the drivers side.
The picture above is an example from the 1958 Buick Body Manual. Comparing it with the cowl tag on both of the 1958 Buicks I have, I would guess that the basic stamping was probably pre-made and the rest was filled in later, probably on the assembly line by hand as each car was built. Each one could be slightly different, so check yours to be sure and use common sense. (The one on my car had the year code ("58") missing from both the MOD and STYLE lines, as well as having the MOD code stamped on the same line as the STYLE code slightly to the right. Check out my 1958 Buick Special page for some actual pictures and related details.) Use the links below to help decipher your cowl tag.
This tag is the second most important tag on your 1958 Buick and the one that is most important from a legal perspective. It's the equivalent of the VIN tag on a modern car - it has the serial number for your vehicle. It also contains the ID of the plant that built your vehicle. It is located on the driver side front door jamb.
The engine codes are stamped into the engine block just forward of the lifter valley cover. The code on the passengers side is the legal engine number and should match the vehicle serial number on the body tag. The code on the drivers side (stamped "upside down" when viewed from the front of the engine) is the production code number.
The codes for Dynaflow transmissions are stamped into the bottom of the transmission case on the drivers side just behind the "high" accumulator. The example in the 1958 Buick Chassis Service Manual shows a single letter followed by a three digit number ("R 016"). I have not yet found any way to decipher these codes.
I have not yet found any references for code stamped on the Flight Pitch Dynaflow transmissions.
I have not yet found any references for codes stamped on the Syncromesh transmissions.
It appears that all 1958 transmissions are physically identical and can be interchanged within their respective type - Dynaflow, Flight Pitch Dynaflow, or Standard. I do not know if there are any functional differences or if there are any distinguishing characteristics between the different rear axles.
Rear Axle Codes
I have not yet found any references for codes stamped on the rear axles for 1958 Buicks. It appears that all Syncromesh cars used a 3.58:1 ratio and all Dynaflow or Flitch Pitch Dynaflow cars used a 3.23:1 ratio. All axles are physically interchangeable, but I do not know if there are any distinguishing characteristics between the different rear axles.
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Page last updated 12/27/2011 10:23:21 AM