Thanks for the warm welcome.
Mark is using a pair of Reinhardt 'Storm' heads. I'm not sure of what he's using for speakers in those Marshall 4x12 cabs.
You can read the specs on the head here:
http://www.reinhardtamps.com/files/Storm.html
The pics belong to Bob Reinhardt, so I'll let him answer that question.
Bob is a personal friend of mine, as well as a member on my forum
http://www.kennyf.com/thecrossroadz . He is one of the nicest people I've ever known, so feel free to c'mon over and ask what you wish. Or better yet, just pick up the phone and give him a call.
Here are a few pics of Mark and Bob.
http://www.kennyf.com/images/MKBR1.jpg
http://www.kennyf.com/images/MKBR2.jpg