Pics of my 66 with the 8' bed.
Notice the hanger is farther forward and a little lower.The support angles are both facing forward.And the top braces are below the bed rail.The fender cut-out is a lot different than the 6' bed shown.The truck had 16" wheels on it too.Maybe why the spare hanger is different.
The last picture is of the in-bed spare hanger on my 68.It also has the under-bed spare hanger.
Mike.