I have them on a 69 Mustang with a 302 and C-4 transmission. The passenger side was the easiest header I've ever put on. Only modification was the bending of a transmission cooler line. The drivers side needed another person to start a bolt while I was under the car positioning the header. You may not need that. It was a tight fit. A primary tube made contact with the bellhousing but not enough to warrent a dent. Also, if you have power steering you should install the drop bracket for your power cylinder. I believe the header will fit without it, but that's a lot of heat for the cylinder. In short, do use the drop bracket. You may want to fab one yourself if you have the skills because that have been know to break. Though, I've used mine for 3 years without a problem. You'll like the headers though. I bought them because they were cheaper than Hooker Super Comps, but I find the quality was just as nice. I ordered mine from Summit. Good Luck,
I have some in my 65 and they are great. As you know, 14 gauge, 3/8 flanges and thermal coated. These babies are not light weights. Very solid. No fitment problems at all. I've had them on about 6 months and they still look new. No discoloring. Got mine from Summit also. About $255 I think. I'd do it again in a heartbeat.
Take a look at "My engine" below. I took the pic last week.