Yup, I checked around. I recall using the tapered screw looking one for some plastic draincock I once broke on a water heater. It wanted to rotate to whatever position the first thread wanted to grab at, because it was screw shaped I had a hard time getting it to go in straight.
Yes, like Shelby said, the square one is what I used after giving it some thought. So after some hammering, some WD 40, and a couple tries, it came out. AWESOME!
After changing the plugs and wires, some of the wires were badly corroded and barely making contact. The plugs must have been in there for a a few years themselves because they all showed signs of rusting. It was missing, quite a bit from time to time, it would stall when you slowed occasionally, and for all this it had some trouble accelerating and it would shift funny.
It's very well behaved now. Took it for a test drive all evening.
Now for the interior light, horn, dash light problem...