I was pretty sure that my truck didn't have a thermostat in it just the way the temperature gauge hardly budged. I didn't want to tear the housing off then find out I had to mail order one, so I took a flier and stopped at my local auto parts store. Told 'em what I had, he looked in a catalog and handed me a new 160 degree thermostat and gasket. Yep, it was right. Gates 33006 if anyone wants to use the number for a reference. Works great.

(yes, I drilled 2 1/8" holes in it for bypass)