First of all, thanks to Kevin for the "new" head. Talked with him at length this morning and only wished he lived closer. Nice guy! Anyway, the head he gave me had a thermo housing on it and, after dropping the head off at my machinest's, I went by the local Napa to pick up a new thermostat. I knew the housing on Kevin's head looked a little different than mine, but I didn't realize just how different they were until I got home. Not only do they look a little different outside, they are completely different on the inside and the way in which the coolant circulates around inside. Now I'm wondering the history on these. I had always assumed my housing was original to the truck (a B2B) or, at least, the original kind. Now I'm not sure. Check out the photos. The first one shows the thermo and housing Kevin gave me (L) and my original thermo and housing ®. You can see (I hope) that the "inards" are different. The coolant is by-passed differently. Also, the thermostats themselves are quite different. In the second photo its pretty apparent that the radiator hose comes in at a different angle. I'm thinking maybe the black housing came off a car as maybe the radiator sits a little lower. What do you guys think?