I currently cleaning out an old shop and found some champion spark plug inserts, but they are not X plugs. So the question is what are they for, the electrode is thinner and longer than the X plug.
They sure look like X plug inserts. Like replacements for the later style X's that don't come completely apart (because of the crimped brass top).
I have no idea, but someone on here will.
i think they would work in the T ,I run ribbed X plugs now as I have 3 boxes of 10 per box for spares but I collect all I can find.