Hot Rods SBC Exhaust Manifolds ID

I have a pair of GM exhaust manifolds that I am trying to identify. I removed them years ago when i went to headers in my 1939 Ford and searching the internet I have not been able to find out what they came off of.

The numbers are: 3646559 with a possible L8 on the right side and 3832461 with a P.H 12 on its opposite side.

I'm guessing they are from the '70's but I'm not sure. Any help would be appreciated.

Thanks in advance.

Fred

 

might have better luck looking at mid 60s stuff. Here's an example....

https://www.lmctruck.com/1960-66-chevy-gmc/cbe-1960-66-exhaust-manifolds

The trucks used straight dump rams horns through 66, full size cars used them through 64, that alternator mount style started in 64? I think. So aside from the pass side having the casting bosses for AIR, which I think came later, they're probably off a 64 Impala or 64-66 pickup?

 

Would the air injection bosses point to 1969 to 1973 or so.

 

Impala used center dumps also to 1970.

 

AIR was around in 66 in California, I think...and many later replacement manifolds had the bosses.

yeah but the driver side was angled back on the 65-70 models.

 

70 1/2ton 4x4 chevy PU used center dump straight down ram horns . I have the ones my dad took of his he bought new

 

I'm always amazed what doing a simple casting number search before you post a question on Chevy parts brings up 3932461 exhaust manifold - Google Search

65/67 corvette exhaust manifold 2 inch 3846559 drivers side and passenger side. | eBay

That doesn't mean that they didn't fit other Chevys in that time frame though. There are always those little nit picking details that mean that they are actually real deal Corvette pieces.

 

Thank you for your assistance, I had searched several websites with no results. I don't use Google, I use Duck Duck Go, it's a more secure search engine, I guess I need to reference Google periodically.

 

Ding Ding... we may have a winner. The AIR provisions point to a smog designated part, maybe from CA or a later '74-ish truck.

I have a '65 or '68 Impala one on my driver side and it is angled back, no extra holes in it. Maybe try to match it up with something that Dorman carries.

 

Notice that only one manifold has AIR provisions, so they're not a matched set....which is pretty common when folks do engine swaps, you find one that fits for each side.

 

This is what I did with my swap. I found a Dorman for the passenger side on eBay, slightly used. It had the angled dump.

I took it to my night gig and ground off all the ugly bumps and script. I plugged the AIR tube holes with steel threaded plugs... my error was not staking them initially. I had one come completely out and another was loose.