Well the M715 seams to have fouled a plug as it has been a little sluggish since the memorial day parade so I figured I would change them to see if that picks it back up. Well I pulled the Autolite 2344's out and went to in stall the spare set I thought I had only find out they are spares for the Dodge M37 I have. So I went to order a new set from Napa online and just wanted to check things out real quick and everything here on the Zone says to use the 2344 but I found a chart on the M38 site that list the proper plug as being the 2407.

And it shows that the heat range is much higher in the 2407 than the 2344 but that they are the same 14mm 1/2" reach.

So I looked and Napa does carry them at the same price as the 2344 but in the pictures the 2407 look like they have a slightly shorter body than the 2344. So I ordered them and we'll see when they get here how they compare. And if I get a chance, I will pull one from the M725 which still has the same plugs in it since it was in service with the Army. (My M725 was a rare Army keep, as it was in use all the way up to 1994 when it was surplused) I found a few references here on the Zone about the 2407 but no one ever answered about them, so we'll see if we have been running and recommending the wrong plugs all these years.