Factory Merc alarm temp switch is supposedly 210? Has anybody found/used a 190? I don't remember the brand, but I found a 200 that's sold with a generic alarm kit.
I'm about to change t-stat housings so I figure it's a good time for new sending units and warning switches.

just about any speed shop will sell the switch in a variety of temps. You will want the normally open type. I'd agree that a 210 switch would be too high for a raw water cooled motor.

Try summit or jegs. They carry set and adjustable temp sensor/switches.

No luck with the big names. Most are 210 or 230.
Found this though:
http://www.spalusa.com/fans/automate...ies/195ts.html
Stainless steel and even shows the Merc style ring terminal. Might be the ticket for $30.

Ordered a pair of 195 and a 1/2 adapter for each. Should go nice with new stainless polished t-stat housings.
I'm not sure what the hysteresis is on the Merc switches, but on these it's 20 degrees. So the switch will close at 195 and won't open again (turn alarm off) until temp drops to 175.