On the 98 3 wire sender Is the third wire a thermistor, like a conventional sender? I was wondering if it would work w/ a stock 62 vette gauge. tx

 

It is the temperature gauge wire. Don't know the output though.

 

It is a thermistor, it will work with your gauge, but it might not be perfectly accurate. I have not tried it, but I heard that the resistance curve was close to the resistance curve of previous GM temps senders, but not exactly the same.

 

my stock 98 ls1 temp sensor worked with the autometer water temp gauge i bought, ive heard that 99+ ls1s need to have the temp sensore that comes with the autometer gage installe.d