headers with 4200 stamped on them.

Anyone know what these might be? they look like hooker but im not 100% sure. I got them when i bought a 318 out of a 70 challenger. They only just fit in the 69 dart i have but will require some "massaging" to clear some of the steering joints and torsions. I might just pull them back out and sell them and buy something that fits better.

hopefully someone here will know exactly what they are.