Header fitment rant, Doug's

Just my .02, but the manufacturers make these parts to fit more than one body style. TTI's are the same part # for A,B,E,F,M and J as I recall, as I expect Doug's are too. This is quite likely part of the reason that there are some fitment issues, along with the variations in tolerances in individual vehicles. I saw/heard, and experienced a small part of the frustration when I volunteered to help a friend install a set of Doug's on his '73 Dart. That car was born as a/6 with a 904. K member was swapped for a V8 unit from a '75 Dart, and a 360/727 was installed. The header install was a 3 or 4 day battle filled with profanity, several tools becoming airborne, a more than a few beers and bloodied knuckles. By the time the install was "done", the amount of restriction created by massaging the tubes IMO negated the whole point of putting the headers on in the first place. My preference for TTI's is based on experience, I refused to buy headers for my Dart before I found them, never had any problems with them in some 10 years of hard use, no leaks, and only moderate discoloring. Have not gotten to the point of installing them on the 75 Dart Sport yet, won't until next year now, but I expect little to no grief when the time comes.
Having said all that, it is unfortunate that the OP had so much trouble with his installation, I have a great deal of patience, but I don't know if I could have tolerated that much aggravation.