My buddy just got a used XXX-NT with the Mach .15 with the blue head on it and the engine is junk. While searching for stock replacements we found two apparently different versions of the same motor. One is a little more expensive and has a black head. The other is the one with the blue head, and that's what's on his truck now. Are their any differences in power, reliability, or tunability between these two motors? Will they both work on his truck? Here are some pics of the two different motors.
Black head:
www.myatomic.com/catalog/viewsku?sku=DYN0882
Blue head:
www.myatomic.com/catalog/viewsku?sku=DYN0880