I have a 396 exhaust manifold, casting # 3909880. According to Colvin in Chevrolet by the Numbers, this manifold is rare and only used from January to May of 1967.

My 3909880 has a casting date of C 20 9 (March 20, 1969). The numbers are clear and not rusted.

The obvious question is how can a manifold have a casting date of March 1969 if GM didn't make it after May of 1967. Is Colvin's book in error? Did the person who put numbers in the mold use a 9 instead of a 7? Or ??

I think you'll find quite a few errors in Colvin's book and many have been pointed out here on TC. Apparently the casting number is correct and that casting is identified in other publications as well. Part number-wise, at least according to my GM P&A Catalog, circa 1971, the part number for a left side exhaust manifold (without A.I.R.) is the same for 67, 68, and 69 Chevelles - #3969909. The part number may have been superceded in the last 30+ years but the book shows the same manifold for those 3 years.

This is a right side, not left side, manifold. Another source I found also lists it as a '67 only part. Still wondering.

Ive seen a couple on ebay lately with 68 and 69 dates..all I can figure is that they are replacement or service parts....being a 66 #874 and 67 #880 look the same and the 68 and up #178 looked different is that the 68/69 #880 manifolds were used if someone came in to dealer with a problem with one under warranty....They have carbs with service dates on them.....why not exhaust manifolds?????

being a 66 #874 and 67 #880 look the same and the 68 and up #178 looked different is that the 68/69 #880 manifolds were used if someone came in to dealer with a problem with one under warrantyI understand the part about the warranty issues, but WHY would GM have two different parts for warranty work when the fit and function are the same? The look was different but not the overall fit. The 1968+ manifold has a cast ridge, but that does not cause any problems when used on a 1966 or 1967 car...

In fact, I would bet that 99.99% of people getting a manifold replaced under warranty would not know there was a difference. Remember, when this would have happened 35+ years ago, these were new cars and people didn't really care about "originality" ("genuine GM" maybe)... Just doesn't seem plausible that GM would have had two separate castings when both would fit and function on the older cars...


this manifold is rare and only used from January to May of 1967.

My 3909880 has a casting date of C 20 9 (March 20, 1969). Maybe its just a "clone" of a rare part??? :D

I doubt if it is a "clone" of a rare part. Although in good condition, the manifold obviously is not new. And if someone was reproducing them, wouldn't they put a "correct" 1967 date on them instead of a 1969 date?

Factory casting error I suspect. Maybe some bleary eyed foundry worker dropped a 9 into the mold instead of a 7 that morning.

At any rate, the date can't be seen with the manifold on the car. But I was curious if anyone else had this casting number with a date other than 1967.

Like I said Ive seen 2 or 3 on ebay with a 7 or an 8 for year and they were clear.............who knows ??????? AS far as manifold for 68 and up being same except the ridge which I belive to be true and they would use them for service replacement, then why would U have a service date on a carb when the only real difference is the list# on choke horn???? the dual feed were 780cfm and the single feeds were all 585cfm. Why would U put a 66 396 4speed #3419 carb on for replacement with a 743 date then put a 67 396 4speed #3837 on with same 743 date??????? who knows its just what they did back in the 60's

Hello. I ran across this site searching for the same answer originally asked regarding the dates on the 880 manifolds. I have one of these 880 exhausts dated L 22 7 and I know it is original. I got it out of my dad's shed where it has been for many years. My guess is that the manifolds were made after May, 1967. Colvin only says they were "used" from January to May. Maybe GM made some replacement 880's after that.