POLL: OEM exhaust manifolds on your 71-72 402 BBC

[71CHEVYSHORTBED402]

Attempting to discover common ground....Possibly establish the part numbers (maybe date codes too) for the original exhaust manifolds.

Note, it's not necessarily what's shown in the 1979 parts catalog, because they may just be replacement parts. Also, 3989343/3989310 is all over the web, but I believe these are for passenger vehicles, and they still might not be the original parts. Also, the same part number can show for those with or without emission ports. I'll start:

1971 C10:
LH 3994045 - No Emission ports
RH 353030 - No Emission ports

Don't know the date codes.

Incidentals: I believe the LH was replaced when the engine was rebuilt in 1993. I seem to remember the original busting when I removed it. Can't say the new one is the same as the old.

[68 50th]

Mine have the exact same numbers, 71 C20. I believe it had the original 402 engine in when i bought it. It still had the heat stove and pipe for example, absolutely no guarantee for it to be the original engine though. All the searches I do for those comes up with 73-76 454 police for 353030 and 73-75 454 police for 3994045.
If that is correct non of us have the original exhaust manifolds.

[71CHEVYSHORTBED402]

Originally Posted by 68 50th

Mine have the exact same numbers, 71 C20. I believe it had the original 402 engine in when i bought it. It still had the heat stove and pipe for example, absolutely no guarantee for it to be the original engine though. All the searches I do for those comes up with 73-76 454 police for 353030 and 73-75 454 police for 3994045.
If that is correct non of us have the original exhaust manifolds.

The 1979 parts book shows the following for a 71-72. It's a little confusing, because it shows the 3994045 "non-emissions" for a 396. Here's the link: http://www.gmpartswiki.com/getpage?pageid=21508

Without A.I.R.
3994045 LH
333846 RH (3916178 to 3994046 to 333846)

With A.I.R.
343787 LH
353030 RH


Like I was saying, the same part number shows on some with and without A.I.R. For example, 353030 comes both ways. Leads one to believe at least some are replacement parts.

I believe the emission versions were added in 1972. As an example, I suppose it's possible the 71 came stock with a 353030, no ports. Then they started to produce the same under the same part number, with emission ports, beginning in 1972...........I believe I've seen the 45 with and without ports as well.

[71CHEVYSHORTBED402]

Mystery exhaust poll..........TTT.

[68 50th]

I did not mention in my first post but mine are also w/o air.

[71CHEVYSHORTBED402]

I have a 3994045 that's off a truck. It Reads L71, which may be December 1971.

I see 3994045 and 353030 everywhere. Coming to the conclusion these came with the trucks.

But I also have a 3994046 that's off a truck. Don't know the code or history yet (it's not L71), but #3994046 looks awfully close to #3994045, if you get my meaning.

[71CHEVYSHORTBED402]

Originally Posted by 71CHEVYSHORTBED402

I have a 3994045 that's off a truck. It Reads L71, which may be December 1971.

I see 3994045 and 353030 everywhere. Coming to the conclusion these came with the trucks.

But I also have a 3994046 that's off a truck. Don't know the code or history yet (it's not L71), but #3994046 looks awfully close to #3994045, if you get my meaning.

The 3994046 I have reads K231. According to this website, it probably means November 23, 1971. Though for all I know, it's 1951 or 1961 ha!....Interesting how the 45 reads "L71", just to add to the mystery.

Still looks to me 3994045 and 3994046 are a matching pair. Not to say 3994045 and 353030 isn't. http://chevellestuff.net/qd/exhaust_casting_by_year.htm

[Blazer690]

Are the 1973 interchangable with the 1972 ?