Identify My Exhaust Manifolds
 

These are the manifolds that were on my motor. I think they are aftermarket because both sides have three bolt flanges (I thought all Pontiac manis had two on one side) and the ID of the collector is 2.315 inches. Plus they look in too good shape to be 55 years old. The part numbers maybe indicate a 67 GTO.

https://i.imgur.com/cqQM6X5l.jpg

https://i.imgur.com/mdGLQQ4l.jpg?1

https://i.imgur.com/ISSFAaLl.jpg?1

https://i.imgur.com/3oCRZdnl.jpg?1

https://i.imgur.com/PZFujfyl.jpg

They do look nice and show up with mostly Pontiac numbers.

The left side shows up as:

9777646 T/8 400 H.O. or Ram Air MANIFOLD 1967

9777642 doesn't show up, but 9777641 does as the RH side, so I'd guess maybe it was a replacement part for a cracked manifold?

That said, I'd guess they are repros based on how thick the casting look.

Definitely repro's
 

Original '67 GTO 400 HO/RA manifolds had 3 bolt outlet for head pipes, so do the '67 repro's. 3 on the right manifold & 2 on the lh began with '68 GTO versions. Yours are def '67 repro's, as original '67's don't have that thick a port flange area or the oddly placed casting run number.

Examining originals or repro's, the outlet on a LH 67 GTO HO/RA manifold is positioned slightly different than '68-69 & '70 (only) RA3 manifolds. Both original & repro '67 LH manifolds positioned the outlet slightly further back in the chassis. A deal I examined first hand decades ago. RARE had supplied a pair of their Dport manifolds for a '70 T/A resto. As a result the curved rear upper casting of the "67" drivers side manifold they suppiled interfered with the positioning of the clutch rod arm on the car's early 2nd Gen Bird z-bar.

As far as brands/different aftermarket castings go, as far back as the early 90's I bought numerous pairs of repro manifolds for customers cars. Some from Paul D (RARE), & some were pairs of '68-69 GTO Dport RA manifolds (through PY). The latter was the only competitor to RARE at the time. Classic of OH was the brand. For ID, Classic's own castings had the GM part numbers cast into them, but a CM instead of GM, was an easy way to spot them.

For the last 10 or so years, seems at least one more entity (possibly Parts Place) became involved in casting up reproduction Pontiac RA manifolds. Hopefully someone can expand on identification of the recent offerings. Do know CCass had a version of RA manifolds going for a while through PYPES.

Ra manifolds
 

I was told that 1970 Firebird Ram Air manifolds had three bolt flange installation versions the gto had 4. I was unaware that it is one year only. I'll post some pics but I did learn that in cold areas the right side cracks easy so when hunting a set its difficult to find a pair. I thought I lost my right side and now own 3 sets. I seen 1 nos left side on ebay and they asking 1800 for it. Seen a set paired up with #12 heads sold as a package in less that 3 hours for $2500 but add said it was from a gto.

Ra3 manifolds
 

There another pic I hope they help you. They do make repops and I seen ceramic coating burned off of repops but repops are 4 hole.

Ignacio, you were told wrong. im betting from your numerous posts, good chance too much ingestion of bunk "tech" & overpriced ads on Fakebook Pontiac sites & eBay... ;) Can relay as a certainty, '70 RA3 GTO & F-body's were equipped with the exact same 70 casting number RA manifolds.

To shine light on more prev off in the weeds comments...
- '68 & 69 GTO D-port RA manifolds have 5 bolt holes for mtg to the cyl head.
- '70 GTO/ Firebird RA3 manifolds had 3 holes on each side to mount to 70 model #12 casting cyl heads.
- Believe there is a slight difference in the shape of the top of the rear port of the drivers side '70 ex manifold. Will compare to originals I have.
- the only HO/RA manifold I've run across with 4 mounting holes to the cyl head was an old reproduction. At least one side (I can't remember which) from one of the Classics brand GTO Dport RA manifolds. Again, ordered those sets many many years ago, & not for one of my own Pontiacs, just remember thinking it odd, as the Classics line of GTO D-port RA manifolds look fairly close to original 68 & 69 HO/RA manifolds

Thanks for clearing that up sir.

So the shape of a f body is different from.shape of gro body and all where 3 bolt your saying? Ok got it.

How can you tell the difference then?

4 version 3
 

These are gto repop 4 bolt holes firebird only 3. II Im not an expert it's want I was told. , they are different. I'd like to know and see a 3 hole gto original and compare to mine. I'm curious if same part number. Those repops are from.ram.air restoration best in business and they have a waiting line. I looked alot when I thought I lost my right original. Inlet almost same but more money and heavier I was told but maybe bad info.

To clear up one issue.

9777641 was the Service Replacement p/n for the '67 GTO RH HO exhaust manifold. It is the p/n you find in the Master Parts Catalog.

An example of how you have to know what you're doing when using the MPC to research OE p/ns.

The CASTING itself was p/n 9777642, the p/n you will find on manifold itself.

PMD ONLY serviced the RH manifolds as an assembly including the Heat Riser Valve. The assembly required a unique p/n, that is true for all of the RH manifolds in that era.

PMD eliminated the trouble prone HRV early in the '68 Model Year on the standard log manifolds.

To the best of my knowledge, up to a point the '68 GTO HO/RA continued to get the carried over RH manifold. The '68 did get a new LH HO manifold, p/n 9791637.

I do not know off hand if the elimination of the HRV resulted in a revision to the HO RH manifold. The elimination of the HRV resulted in a new p/n for the log type RH manifold (pretty sure about this, I used to thoroughly research the log manifolds but going by memory at the moment).

Like the LH manifolds, the new RH log manifold was no longer an "assembly", so was serviced by the same p/n as you find on the casting.

The first gen 'birds used the same HO manifolds as the big Pontiacs, they did not share with the GTO (A body).

In '70, the F Body was able to share same manifolds as the A body (both log and HO/RA).

The round port manifolds are a separate discussion.

I'm a little confused as to what you are saying when you say "these" are 4 bolt holes being GTO repops vs 3 bolt holes being Firebird.

OPH posted the hole count for the "flange" to head and also the bolt count at the outlet by Model Year. Matches what I know about it.

Your pix show 5 bolt holes for the "flange" to head and the p/ns are correct for the '67 GTO application (and '68 at least until they eliminated the HRV).

The first gen 'birds used the big car HO manifolds as I mentioned. These had 6 "flange" holes and 2 outlet holes.

The '67 used 9779495 for the LH and the 9779494 for the RH, with the same confusion as for the GTO since the RH was an assembly with the HRV and in the MPC the service p/n shows 9779493. You'll never find a manifold with this p/n on the original casting, only 9779494.

The LH stayed the same thru '69. The RH got a new p/n when the HRV was deleted and another in '69. I believe the flange and outlet hole counts were unchanged however at 6 and 2.

OPH has a lot more parts experience than me so if I stated anything incorrectly, I'm sure he'll be able to offer a correction.

John and Ignacio are talking about 2 different flanges. John stated he believed that his were reproduction due to his having 3 bolts from the exhaust flange to the down pipe on one side. Originals had 2, although if I remember correctly it was 2 on the driverside and three on the passenger side. in 1970 anyways. I can’t speak for the 68’s honestly. I remember having this issue with the trans am because I didn’t have the correct flange for the reproduction ones we installed to get it running and had to have one shipped to me.