Quarter Window Issue

What is your end objective? If your wanting to modify the vehicle, then I would not be concerned. You can change things as you want them. If your intention is to do a detailed, concourse restoration, then you will have some parts hunting to do. It's not uncommon to find some components changed due to the interchangeability of the items. Having the upgraded disc brakes is a good safety item. Changing the seats should not be to difficult to do.

Yep, my driver's door is off another 67 and I think the guy that salvaged it also took the trunk and passenger quarter panel as well.

My 67 is a bit mixed up also, it has a steering column from a 68. It happens and it will only matter if you care about it. So long as it all fits right and you are happy with it, then so be it.

The 65 Shelby quarter windows would be from a fastback. If yours is a fastback then it would have had the vents. I don't think they had Shelby convertibles until 67.

Is your car a coupe fastback or convertible.

I'm sure over the years though people would replace parts with salvage yard parts or whatever was more easily available. So, to come across different year parts on your car is not uncommon.

I noticed the same thing - Shelby on the vent window holder, about an 1" L holder preventing the window to be "derailed". I think you have OE windows, not Shelby. Ford just used these little suckers for whatever reasons

If the door panels are '68, with the longer arm rests, the 1967 door panels WILL go on those doors and the shorter arm rests for the 1967 will also. The clips that hold the 1968 arm rests have to be repositioned into the lower rectangular cutouts in the doors that are positioned for the 1967 arm rests. A 1968 door IS a valid interchange for a 1967 Mustang. Coupe Convertible and Fastback doors are all the same within the same year. It's the glass that is different in each of them. A 1967 door IS NOT a valid interchange for a 1968 Mustang. If you do this kind of swap you will have to cut the rectangular openings for the clips that hold the longer arm rests yourself (again, not a valid interchange).

The 1968 style disc brakes were a preferred swap to the 1967s because they are (were)easier to find. The 1968 and 1969 disc brakes are the same, Mustangs and Cougars. In 1970 Ford made the spindles larger and the bearings also. One thing to be sure you have on the car if it was converted to disc brakes from a non-disc brake car is the rear brake proportioning valve. On a 1968 and 1969 line block the proportioning valve is installed on a 45 degree angle to the upper end of the line block. 1967 Mustangs had the proportioning valve installed up over the attachment point at the rear-end (where the steel line goes into the rear line block).

I really never looked at any of the rear quarter windows I ever pulled out of the many Mustangs I used to cannibalize back in the 80s. I do know that the rear quarter Coupe glass and Convertible glass is different though.

1966 seat frames and 1967 seat frames are identical, to the best of my recollection. The 1968 seat frames have the seat back locks on them so I believe they are different. In order to make the seats look right for the 1967 you need to buy and install the 1967 seat foam and seat covers. Check that to be sure, the foam may be the same. Remember, you will need to pull the stiff wires out of the old seat covers (these wires sometimes stay inside the cracks of the seat foam due to fabric age and rot) and install it into the loops on the new seat covers, and hog ring it to the seat frame in the opening of the seat foam to give the seats the correct form when they are recovered.