The 5-window pickups were the deluxe versions, so chrome bumpers could have been normal on them. Since you have chrome bolts, my guess is that someone replaced your chrome bumper with a painted one and kept the old bolts.

Any 1961-1964 Econoline front bumper has the same bolt pattern as yours.

You could also use a 1965-1967 bumper if you also use the 1965-1967 bumper brackets as well. The holes in the frame are the same.

Some prefer the 1965 -1967 front bumper since they are heavier steel and narrower. The 1961-1964 bumper seemed to stick out the side of the van farther than it needed to.

I think the rear bumper for the pickups is the same from 1961-1967. It is also the same as the vans from 1961-1964.