I want to get it right even if it isn't screaming fun... There are metal plugs on the "special 261 housing" and on the water pump. Is that what you mean? What is the outcome of using the regular 235 thermostat? Where do I find a 261 special thermostat? The 261 in the firetruck was added later in the sixty's so it has been a pain to address the issues so far. I'm happy with it but I wish I knew this stuff when I put the thermostat in. I just figured it didn't have one so if I put one in a 235 would work just fine like in all my other cars... Wrong answer. Thanks for taking the time with me on this one.