I wish I could. Ford evidently did something different for 66 289 GT "H-Pipes" with smog and what was determined by local Mustang shops back in the 80's is there was a "shape" difference. It's could be nothing more than a different bend.
Jim
OK, this makes some sense. Obviously, if a different engineering number was issued (C6ZA-
H), there has to be some sort of difference.
Speaking to the "It will not fit 67-up" statement mentioned in your earlier reply, I will add to that information provided to me from Scott Fuller yesterday. Scott claims the C6ZA
-H H-pipe has the exact same bends as the C8 H-pipe used on J-code 68 GT Mustangs, though the spot-welded on limiters are in a slightly different place. As you see in the images I have posted, the limiters I speak of on the C6-H version, are located on the bottom. Scott said the C8 version, those limiters are located more outboard on the pipe, not directly on the bottom. I questioned this detail with him again, asking that I thought those welded on tabs were for indexing the correct rotation but he said no, they are simply limiting stops so the pipe is not inserted too far or too little. He added that there are other Mustang applications wher they are used for both rotation and depth of insertion, but not so in this usage.
Scott went on to say that he thought he already has 2 of these very same C6
-H H-pipes and used them as reference examples for making his version of the C8 H-pipe and has confirmed them to be the same (with previously noted differences in the stop/limiter tabs). Scott mentioned he sells the C8 version he makes to fill the requests for H-pipes to all small block requests that are not Hi-PO applications, meaning that if you have a 67 289 (A-code or C-code) car that would not come with dual exhaust originally from the factory , he would sell you the C8 H-pipe and the pipes listed in his online catalog by year, from the resonator pipes-back. I cannot answer if he has or sells the other C6
-F H-pipe you mentioned you have Jim. That suffix pipe did not come up in our conversation. When I was done, my take-away was if a person requested a 65-70 small block 289/302 (non-boss), you got his C8 version H-pipe. You can look at his online catalog again and when you shop for a non-Hi-PO version H-pipe, as of yesterday (3/8/18), he shows no listing. I did ask about the web catalog not showing them available but he said he sells them the C8 version when asked by phone or otherwise.
Summary: According to my understanding of my conversation with Scott Fuller: "Yes,
it will fit all Mustangs 65-70 with a basic 289/302 dual exhaust, though it can have the tabs welded in the different place and a different engineering number for any 68-up usage".
Again, I can believe your statement from your Mustang Shop friends also, but it would help to have more than just a simple possibility of a "different bend than a C6-
F" pipe, to Explain any different visual aspects better. Nonetheless, according to Scott, it sounds like it will FIT any non-smog application as well, like what is typical in the Ford Service Parts catalog superseded numbering system. Perhaps somebody could do some MPC research on the numbers from a few years of the MPC (66 though 70 perhaps).
(On edit, John has provided one of the MPC references that helps)
