Holy Smoke!!! I wish I had known how to reach you earlier, but this is outstanding! If we were in Japan, you would be declared a Living National Treasure or some-such! I surely appreciate your effort on my behalf!

The brake switch, which is pushrod acctuated (I'll come back with a web-address that has a picture; my powers of description are insufficient, because I'm sure you know the switch), was indeed something that the experienced local parts-man said was not ordinarily associated with a 1968 truck. But, and I'll have to have another look to be more confident of this, my impression is that the truck is pretty original and not too cobbled-up by previous owners. I haven't picked it up yet, not wanting to drive it without brake lights.

Further investigation showed that the brake switch itself was okay (after I'd bought a new one on the owner's advice)(but that's fine, they don't last forever). The problem was where the brake wires go through the turn signal switch. I removed and disassembled that switch, hoping I could save it, but it was irretrievably worn out. Thanks be, I found Bill McGrath (I think that's right, must double-check) at Early Ford, and his all-new 1956-60 switch.
My (when I pick it up) rig is floor-shifted. I'm assuming it's a one-ton P350 because it has single 16" tires on one-piece rims on the rear axle.

got a battery warning, be back tomorrow. THANK YOU!!!