Self adjusters were not available for F100's until 1964. These self adjusters only work (if they work at all!) when you back up and step on the brake pedal.

The adjuster cable (there are 4, one inside each drum) is notorious for snapping. This may allow the cable guide to float around inside the drum.

What happens when this little charmer gets between the shoe and drum and you then step on the brake pedal?

The cable guide chews the hell oughtta both the shoe and drum. And, the adjustment wheels rust up, rendering the whole set up inoperable. NAPA once sold a kit to remove the pesky self adjusters.

Forgetaboutit! IMO, they're more trouble than they're worth.