Yeah, its all coming together now. I went out to the back forty and pulled another 261's thermostat assembly just so that I was sure about my numbers. Both are from 1959 and 1962 261 engines. My engines did not come with trucks so I have no idea what model they are off of. I am cleaning them up and pics are forthcoming. Maybe tomorrow since I let the day get away from me.
Interesting about the two port water pumps. I have two of them, different styles. It doesn't matter how you connect them because the ports are in a cavity together. You can put your finger in one hole and out the other.
Tim if yours are a different size than described above, please take pictures so they can end up in the document too. Both of mine have the exact same dimensions as the 235 IN/OUT.
261 Housings Casting Numbers (same look but different numbers)
Set 1: Bottom #1 is Casting No. 3764748 Top #1 is Casting No. 3764749
Set 2: Bottom #2 is Casting No. 3757233 Top #2 is Casting No. 3757230
Both have 1/2" NPT ports and came with 3/4" hose barbs.
Also, there are two water pumps listed by Dave that work with his adapter. One is the 1953/54 one I mentioned (3/8" belt) and the other is 1941-52 (5/8" belt). Get them at RockAuto because they only cost $60 or so instead of the $130 the vendors charge.
Thanks to both of you for helping get this documentation squared away. Accuracy is everything.
