While doing some more searching through the forum I ran across a thread by IronCanine on the subject of heat stoves. davischevy posted a couple pics of his 56,000 mi C10 and it appears that all screws across the top are indeed hex head. It appears however that the two for the pipe have larger heads than the others. Looks like my two Phillips screws are OLD replacements.
Here are davischevy's pics.
