Diesel Bombers - cup or head?

I've put hours of digging through the internet the last couple days and couldn't find a situation quite like mine.

I have a 2005 ccsb fully loaded f250 I totaled(parting out) do to someone driving under my cab. so I picked up another loaded 05 ccsb built by my buddies dad and then sold to someone else. it has a fully built trans, sticks, and a wind pump well seeing as I knew who built it for some reason I didn't think I needed to check it over as well as I normally would and for some reason didn't check the way the coolant smelled.... silly me

well I got home and decided to check it and there was diesel in it. ill give the kid props, he did a good job covering that up. the only time I can smell it is under hard acceleration. the truck does not run hot, it doesn't white smoke, doesn't burn coolant, doesn't seem to be low on power or anything just diesel in the coolant. I had to work Friday-sunday(today) and I wasn't to concerned with it and planned to pull it apart the coming Monday. I had it warming up in the driveway before work this morning and walked out and the driveway was covered in coolant. I don't know if a hose busted, it cracked the degas or what. I wont be able to look at it until I get off at 1130 tonight. so what do you guys think?