The 7th Material Squadron was the ground support for the 19th Bomb Group's heavy bombers the B-17. They were the guys trained to keep the aircraft flying, instrument and engine mechanics as well as other specialists.  The B-17's at Clark were not the B-17G pictured above, this is a later version but and help me out on this on guys, I believe the B-17's at Clark were B17C's.  There are no longer any B17C's still running but this B-17G tours around the country through the Collings Foundation and offers rides.  My brother and I both have done it and I just can't describe how great it was.  Living history like that made me feel closer to my dad and what he went through than reading all of my many books about WW2, a truly incredible experience.  Its expensive but the best birthday present ever!