454 carb has 2 sending units in the tstat housing. Which is for the alarm and which is for the gauge, or does it not matter?

i think the alarm has the blue stripe and sending unit is plain brown

Just ground the wire to find out.

+1

The sending units are different...does it matter which is hooked to which?

yes it matters. One is basically a on/off switch for the warning buzzer. The other is a resistance type for a guage.

My gauge sensor looks like a 3/16" threaded bolt. The alarm sensor is oval shaped.

Oops. I was thinking you were trying to figure out which wire was which. As Wes said.

ok, so which is which? They both have the same connector. I have to pull my thermostat tomorrow, as I think it is stuck open, so I will be able to look at the inside of the sending units. But I don't know what to look for?