I am not familiar with that X term, but I started in auto parts in '81 and they were still stocked some of the multi-piece type plugs.
We got in an AC plug one time with no threads on it.... I had more fun with that plug telling guys the '80 whatever year GM cars were coming out with press in plugs and you would have to go to the dealer to have them changed(back the you had to change plugs pretty often). They would get all fired up and raise cane about tapping out the heads and so forth...
Hey I remember those plugs. You had to cut the electrode end for the depth then use a die to thread them to the engine. Just like when they put the cardboard tube on them to protect the threads and electrode, you pushed it in til the threads grabbed then screwed it in. The tube compressed to make the gasket.
__________________
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989, Seasonal since 2000.
Car Shredder Op/Tech, Scrap Metal Recycling - retired
2011 Flagstaff 831 RLBSS
Linear Mode
