I don't know, but I'm bummed that they changed the stock stamp on the Challenger. I liked using the straight line design to aim at the chains. I tried switching to a Voodoo and a Wizard lately, but I'm back to Challengers again and it feels like coming home.
Magnets have had few stamp changes. This makes large time frames to try to pin down fight differences (as oppose to 10,11,&12x's). The only three stock stamps I've seen were the "pulse", the "4chains", and the current.
While I do prefer the chalky feel of some of the older magnets and challengers, I can find new ones that are simillar enough.
As far as the ion suggestion to replace a challenger, if you're a push putter, a stiff, beaded disc is most likey better.