I've seen those spark plug things in the back of Chilton's/Haynes too, but I have to go with Broddyman on this one. Is the center electrode mashed down? Sure looks like the gap is WAY to close. If you have a way to clean them, you can try to use them again, but I'd get a new set and gap them to .030-.035 or .050-.065 if you've got an electronic distributor.
If you have questions on what plugs to use, or heat ranges, ask away. I dropped a set of used (8 valve) Saab Bosch Platinums in my Luv and it ran fine. Sometimes you just have to use what's on hand, right?
I'm guessing your cap and rotor are relatively new? I've always used a pocket knife and brake-kleen to clean mine up. Just scrape the crust off enough to get the contacts shiny (don't forget the center one on the rotor), after scraping, spray it with
a little brake-kleen. I set the cap right side up and let it air dry before reinstalling. If you don't have any brake-kleen,
DRY compressed air will work too. Don't use any sort of cleaner/solvent that will leave a film or you risk tracking in the distributor cap. This has been my method, but some of the other folks here may have a more 'expert' way to do this.
Ohm out your high tension leads (spark plug wires), they should be less than 2 Ohms. Cheap leads tend to use a sort of fiberous carbon core with the end bent over and pinched into a metal clip that attaches to either the plug or the cap. Tug test these gently, they are highly suspect right out of the box, IMHO. If you suspect a damaged HT lead, start the truck in a very dark place and open the hood. Listen for a pip-pip-pip-pip sort of sound and watch to see if one of the leads is arcing to a ground on the engine. If one them is worn or cracked enough to short to the block, you will definately see/hear it under the above conditions. Be careful!
If you're still running points, point gap is .016-.020, dwell is 47-57 degrees.
As far as additives, or crappy California gas, go to WalMart or your local farm supply and get a $2 box of mothballs. Make sure they are Napthalene, not the 'non-smelly' kind. It should say right on the box. Drop one in the tank for each 4-5 gallons of gas and see if that doesn't take care of the problem. Don't do this if you've already got other additives in the tank. HEET is the one exception. As a testament to this, I drop 5 in each of my mini-vans every time I fill up. I've been doing it for over a year, still have half a box left and not one fuel problem. My mileage also increased, but that's another topic.
Finally, is this just one plug, or do all of them that look like this?