Everyone,
Thank you for the responses so far. Ty's purple head is not one I have see before. My current SilverFoxx 35 has a purplish head, but it started as blue and has shifted color a bit over time. As for heads on the Fox 35 I know of the standard high compression head that Fox made (have not seen one in years though- Bill Morbacher confirmed that they did exist when I asked hima couple years ago), the Blue Magic where the top of the plug points rearward, Randy Smith's head where the top of the plug points in the direction of the exhaust (not sure if this is the same as what Larry Foster used on his, but they look a lot alike), the Fox/Denny button style head that pointed straight up and one I found a few years ago that looks like a Smith head that was not completely finished.
John