NOS? 1967 resonators on eBay
 

I have never seen original full size tail pipes with resonators . Are they? They appear welded on one part and I always was told none of these exhausts were ever welded at least on the A body cars. If so quite different than the design of the 69 GTO versions that are on my Gardener exhaust.

https://www.ebay.com/itm/26573092317....c100667.m2042

my dads 68 428HO bonneville came with them.

The sound from these resonators makes the Pontiac sound so sweet! I had them on a 1966 GTO back in the day. Best sound of any muscle car in my opinion. I also liked the sound of the Roadrunners. Not sure if the 1967 GTO came with resonators from the factory or not.

That looks correct

67 GTO cars had resonators on the factory automatic cars. If I read the 67 GTO Assembly Manual correctly. it says Resonators "EXC. H.O. ENG W/MT & 242 W/MT. I still have one of my original Oldberg version from my 67 w/THM.

I'M SEEING IT LISTED AS ALL DUAL EXHAUST.

My 70 Bonneville has resonators. At one point with a new exhaust I tried without and hated the harsh sound. Installed resonators and as previously stated, sweet sound!

The master parts list did have HT (Hydramatic Transmission) after the GTO for 67, suggesting the manual transmiision GTOs would not have them.

BTW, Thanks for uploading the parts list. It helped solve a mystery. I have these CDDC resonators dated H3E and H4C. I originally thought they were for a GTO but the outlet pipe was 1.75" dia. The list shows P/8 cars used the smaller pipe. Anyone need resonators for a full size?

Resonators were standard issue on almost all full-size Pontiacs in that era. Many A bodies had them too but it varied by year, trans and engines (68 tuning pipes for example) and typically only on dual exhaust. Even first gen Firebirds had resonators when equipped with dual exhaust (although in that case they are ahead of the muffler).

Back to full-size cars there were several versions in the 65-70 generation: wagons had a unique set up with the resonators being mounted diagonally on the axle crossover, the long wheelbase cars have longer resonators than the standard wheelbase cars. There were a few different diameter tailpipes associated to them; single exhaust and HO cars typically had 2.25” and non HO cars had either 2” or in some cases 1.75”.

69 GP’s had them except with 428 HO, 69 GTO and LeMans-Tempest had them except for manual trans GTO and single exhaust

Factory Resonators - Tempest Series
 

All 1966 (automatic and manual transmission) GTO’s came with resonators.

All 1967 automatic GTO’s came with the resonators.
Manual shift ‘67 GTO did not come with the resonators.

P & T with resonators are a must have in any restoration. Over the years...I kept purchasing them, but the wrong ones!! .... now have 2x 9798281, 1 x 9797127 which fit 52/66 but need ones for 62's. Also have 5 x 9784753 that I have no idea what model they fit to. If your interested in any let me know.