2005 F-350 6.0 Diesel w/ 120k mi

Ok, I've read about a million posts here (including the tech guide) about no-start problems, but......

Most of the problems seam to be with a truck that shut down while running or developed some other running issue. I haven't found any other posts with a problem exactly like mine.

My truck started and ran fine yesterday- no problems. Came home and went back out about 1/2hr later and it wouldn't start. It will crank like he**, but won't start for anything.

No engine or dash warning lights when it was running. I hooked it up to my OBD2 scanner and there are no historical codes or current codes, I ran the KOEOff scan and got nothing, but of course I can't run the KOERunning diag's when it won't run.
I have tach and oil pressure showing in long crank, and I've checked fuel pressure (50psig) after replacing both fuel filters, and then purged the system. I pulled the ICP plug and tried- nothing.

I did a quick wiring harness check, but not exhaustive yet.

Before I start disassembling the thing, has anyone had this problem? Seems weird I haven't had any running issues and all of a sudden it just won't start!?

I recently replaced the oil cooler and installed the EGR delete kit and it's been running fine.

Note: It was about 100deg outside when I came home yesterday and the truck only had time to cool off a tiny bit before I tried to leave again, so I don't think this is a cold starting issue- like GP's or related.

Anyone.......anyone??

Thanks in advance!
Jay