Sorry Guys, I've been away from the site for medical reasons and didn't see the questions.
I have been using these headers so long that I can't be positive about the year. I am reasonably certain that they are from a 67, but because I have the stock steering box, I had to cut the back two pipes on the left side and weld them in a little tighter to clear the steering box. The modification shouldn't make any difference as to whether you are using the front or the more modern side engine mounts.
I have used both truck and the car headers on the truck because I put the engine in in 1970, and have worn out a few sets.
The headers have tons of room, you can slip both sides in without moving or disconnecting anything. ( my engine has the front mounts)
It isn't possible to get you a good picture right now because I am in the middle of trying to get a garage built and have some serious health issues.
I'll get a pm to you when I can move the truck. When are you starting the swap?
Bob


55 Cameo 396 TH 400 with overdrive
65 Caliente conv
67 BB Caliente conv
67 Mercury 1 Ton
76 GMC 3/4 ton 454ci
84 Buick Turbo Regal