Part of the problem w/ champion is that the plug type say xlm15 isnt the actual part number for that plug, the part number is a 3 digit one such as 603. So a 603 is a xlm15
they arent 2 different items.(I used those numbers as an example, not as a fact). Online info from all the plug manufacturers is incomplete at best. I hope the national back order isnt a discontinuation. Since they seem to have the same specs what about the 2384 are they avial, an the 2385 is the same jus one step up in heat range.