68 Rear Bumpers, Date codes....
 

About 5 years ago somebody here on the forum shared a picture with me of the date stamp on his original GM bumper. His stamp was 11A7 I just Assumed that meant First week in November 1967. I recently mentioned on the other bumper thread that I had an original 68 rear bumper from an April built Lemans, But looking closer today I see the date on it is 4A4 What the heck is that?

I am now thinking my first assumption years ago was probably wrong. I know this was the original bumper to the car. Anybody know? I'm stumped....

Here's the picture I was shown:

http://forums.maxperformanceinc.com/...4&d=1376263833

Here is the one from the April Built Lemans:

.
http://forums.maxperformanceinc.com/...2&d=1518386100

My guess is the A is for the stamping machine or station....possibly similar to how the body panels are coded. The preceding numbers may be the month and the following numbers day of month?

The stamp on the bumper from my car is 10A16. Probably not original to the car though...

https://uploads.tapatalk-cdn.com/201...31972baad7.jpg

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Wow, thats a nice clean stamping! All the extra holes for a licence plate?

What's interesting is The bumper I have that came on my GTO when I first bought it was replaced sometime I think in the 80's when the car was repainted. I assumed all these years its a repop. I have been comparing it tonight to this rusty 68 original bumper I have & so far its identical in every way. Even all the edges of the metal are the same. So, either it's a really well made repop from many years ago, or its a GM replacement. It has a stamp in the same place but looks like 2A0 which, zero makes no sense. But, again, this last one could be a non GM bumper. just weird it has a similar stamping & in the same place.

I still have some paper work from the car the 4A4 bumper came from. I'll see when it was built. I know it was April though. Car was crazy rusty & I stripped it for good parts & junked it many years ago.

I have a re-chromed OE 68 here, says 5A9J

Not seeing a pattern here so far.

Sure you are. The first set of numbers is the month. Followed by a letter (usually an A or B, which I take as a shift). Followed by another set of numbers, which is the day. And finally, if happened, another letter (which could be the machine used to stamp it).

I just dug out the records I had kept. The 4A4 bumper I listed above came on a car built 04A & registered to my father in-law on April 20th. Looking at a 1968 calendar, the 4th would be a Thursday & the 20th was 2 weeks from the following saturday. Pretty amazing how quick that was in his driveway.

Interestingly Dataway's bumper is also a Thursday. Probably just a coincidence.

Is it safe to assume the other two examples with months 11 & 10 respectively are 1967? I would guess by those months they were already stamping the 69 model year bumpers? If it is those both land on a tuesday.

Anybody else have some examples? :)

So it doesn't look like there was a year designator?

Mine also has a K K K stamped on it in kind of a random arrangement, did Kelsey Hays do any of the bumper stampings?

That makes more sense than what I was thinking.....and works better since most all the off parts have the "A" stamp. Sometimes there is a trailing letter and sometimes not. Not sure why it varied. I had read that sometimes the stamping operator would monitor the crispness of the date stamps and then adjust the machine when needed. That last letter might be used for that purpose.

As best as I can tell, there are two date formats used on the formed metal parts. The panels formed at the Fisher plant and used to make up the body shell are Letter and number where Letter appears to be the stamp station and number is the week of the year. Sometimes these panels also have a 4 or 5 digit number preceding the letter and I presume that to be a part number. We also saw in a separate thread where some parts include an L or R for left and right. Those were found on the rocker panels of a 67 car I believe...

The "off parts"....those made at the final assembly plant appear to follow the format discussed here. Number-letter-number-and sometimes another letter. I think it is reasonable to suppose the first number is month. Letter is shift. Second number is day of month and last letter could be the stamp machine/station and used as a proof checker.

Here are some more stamps of off parts. 5A14M is the RH fender from my May 27th car. 6A23 J is the LH fender from a late July car. Notice how the J is separated from the normal stamps and the impression is much deeper.
The 10A17 is a front inner fender...perhaps from the same car that the 10A16 bumper came from.

Parts with an October date would have been stamped in 1967 for use in 1968 model year cars.https://uploads.tapatalk-cdn.com/201...5e086b9c06.jpghttps://uploads.tapatalk-cdn.com/201...b1546d9889.jpghttps://uploads.tapatalk-cdn.com/201...45a89ec4a9.jpg

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As long as somebody doesn't post a 13A32 it seems to make perfect sense.

I suppose its likely the stamps were used internally & weeks to months were a long
period of time in that environment. Probably no need for the year as nothing would b
e sitting for that amount of time.
Kinda like the grocery store putting the expiration date on a loaf of bread. Really shouldn't need the year :D
Twinkies? better put the year....

What do you guys think about this bumper date??

Is that B typical?? July 22nd, but Haven't seen a B yet

http://forums.maxperformanceinc.com/...6&d=1531424196

Looks like it could be "B". Second shift?

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It could also be a revision code. At the beginning of the model year would be an A, then when extra holes were added or a repair to the stamping die or ..., it would change to the B and so on. But, I'm still thinking 1st or 2nd shift designate.

If its revision based, then all of the "B's" would have later dates than the "A's"

4B4 on my original bumper. It's an 05B car.
As for fenders, passenger=5A2B
Passenger=A26M

Which passenger fender is the left one, er uh, which passenger fender is on the right, um, which right fender is on the left, I mean, which left fender is the right one...:faint:


Frank

Oops... Ah, who cares anyway..I mean really...lol

:phone:Hello, yes I'd like the number to someone who cares, :cell: I'm sorry that number has been disconnected.....


..:pound:..
Frank