>>> Though your comment does inspire me to get a 1/4-32 die just to have one. My hobby shop has a Higley die for $14 >>>

Here's a little more poop then on why threads strip out of the head often. What happens is sometimes when we unscrew the plug, it has become welded to the aluminum in the head so the aluminum comes out with it. That happens because of poor fitting glow plug threads that cause little tight fitting spots. Then with a hot or lean run those tight spots become even tighter causing the bonding or welding of the plug and head together. Simply running new plugs into the die eliminites this from happening.

The local screw products store ordered my die for $9.00.

Ernie Misner