Updated SPITFIRE HEADER INSTALL 63-66 A-body
I have them on a 70 Duster with power steering. They fit fine but putting exhaust pipe to the driver's side is somewhat difficult.
at least in my case you could keep the studs in the ends just by cutting them down a little. I have magnum heads on my engine that don't have water jackets in those holes so they are all bolts.
One thing I would also do is spot weld the header collector bolts to the headers to make it easier to hook the exhaust up.
They're 1 5/8" primary tube with 2.5" collectors unless they've changed since I got mine. I still may go to TTI's at some point on my car if I can't improve the driver's side dump pipe...its only 2" on my car.