Guys I made progress on the "What it is" sound. It turned out to be trivial. I am 99,99999% sure Mark used his original 1961 on it, with the neck/middle pickup. The 1961, being a vintage Strat, has much weaker pickups than Texas Specials. Weaker means more transparent, less thick. In a funny way, a vintage Strat in neck middle sounds about as full as a Texas Special equipped MK Strat in middle bridge.
You cannot get that exact What It Is tone with the MK Strat. It will sound a little too dark and too thick.
Why Worry on All The Roadrunning is definitely a stock MK Strat with TX Specials. I tried to get that tone with my Masterbuilt 1961 Strat (vintage spec). No chance. My Masterbuilt sounds like early Dire Straits, can't help it
The MK Strat immediately delivered.
I will open the can of worms and say out loud proudly: a real MK fan needs both the MK Sig for the modern sound as well as a 1961 copy for his old sound.
Gosh I love Strats!!!