Yeah, the diagrams for shocks I see for that era truck have eyes and thru bolts on both ends (like Gord's link show). So the mount would be more like a "U" shape with the shock eye between them. Is your front shock mount welded to the frame or riveted? Hard to tell from your picture.
To me, the front looks like it has the same type of weld as the rear. I still think that the rear was probably the original but its hard to tell due to the bracket being bent and missing a chunk.
