Muffler date codes?
Thread Starter
Melting Slicks
Joined: Apr 2011
Posts: 3,496
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From: New Jersey
Muffler date codes?
For the NCRS guys; I have a chance to pick up a set of GM original mufflers from a 1986 for my own '86. My question is this: It seems like the part numbers match up; but are the mufflers date coded, and if so how do I read them? Thanks.
Team Owner
Joined: Sep 2003
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Post snapshots of the information. Different vendors use different formats for date coding, it's usually easier to actually see the information.
Race Director
Joined: Aug 2000
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original OEM mufflers are date coded. here's a pic of my (steel blue) 90's muffler part and numbering information. the bottom row of numbers, "6 1 170 0," and "3 2 170 0," are the mufflers date code information. the 170 is the Julian date (in this case, june 18th), and the "zero" is the year digit - as in 1990. the "6 1" and the "3 2" is most likely some production information - production line, shift, ???, etc..
my mufflers were dated june 18th (1990) - from what I remember, my 90 was a july car.
my mufflers were dated june 18th (1990) - from what I remember, my 90 was a july car.
Last edited by Joe C; Aug 20, 2015 at 07:29 AM.
Thread Starter
Melting Slicks
Joined: Apr 2011
Posts: 3,496
Likes: 475
From: New Jersey
The mufflers I am looking at have date codes similar to these. The codes are 142 and 147 and the year code is a 6, so they were produced, by that logic, on May 21 and May 26 of 1986. My car was produced on Nov. 22 of '85. These will not pass muster in terms of originality judging, I suspect. They have to be dated within six months prior to the cars build date but not after, correct?
Race Director
Joined: Aug 2000
Posts: 11,470
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correct - it used to be 6 months, but I'm not sure about that on later model cars. GM doesn't like to keep inventory, and I would suspect most parts are within a month, maybe two. as I'm getting into my 85, I'm finding most everything is around 2 months. I haven't been involved with NCRS for years, so I really don't know the current guidelines. the 6 month thing is really a guide line. my 69 corvette had a water pump (original OEM) that was dated outside the 6 month window. no flames, but I'm glad I'm over that matching numbers stuff!!!
Last edited by Joe C; Aug 26, 2015 at 05:19 AM.
