RH Exhaust Manifold 65-66 GTO
 

There was a design change made on the RH (passenger side) exhaust manifold in ‘66.
The ‘65 RH manifold had a round casting at each end, whereas the 1966 had a revised, stronger casting at each end.

1) 1964 RH exhaust manifold.
2) 1965 RH exhaust manifold.
3) Factory photo of a 1965 GTO engine.
4) RH manifold on Scott Tiemann’s ‘65 show winner (Pontiac build).
5) Same showing the round front casting on the ‘65 manifold.

My 11A Baltimore build ‘65 Survivor also has this round casting.

1966 RH Exhaust manifold
 

Photos showing the revised, stronger manifold casting at each end on a ‘66.

1) New 1966 GTO engine with the revised manifold.
2) My 01B Fremont built Survivor RH manifold.
3) Front of the ‘66 manifold showing the stronger/heavier casting.
4) Rear of the ‘66 RH manifold.
5) The 1967 also used this revised casting on the RH manifold.

Great info! Didn't know this. Thanks for sharing

My '65 was a late build, mid July 1965, and it has that '66 revised stronger design right manifold. I'll take some photos of it this week and post.

The round earlier castings are more elegant.

That is if an exhaust manifold can be considered elegant. ;)

My 65 GTO was a late May 1965 build and it has the 66 revised stronger design right manifold.