I have posted this many times. You most likely will not find a sender that is
compliant with older cars,so....You get what they sell you, install it and
run the car and see where your gauge goes. MOST of the time the gauge will read too hot. Make sure you know what your temp is by using an IR temp gauge.
Get yourself a 2.7, 3.0, 4.0 and a 5.0 ohm resistor, usually 1/4 to 1/2 watt
will be ok. When your engine is at temp (180-200) put the lowest value resistor
between the sender and the feed wire, and see where your gauge is. Midscale
is what you want, if its not there, go to the next highest resistor. As your
temp gauge will be midscale at normal temp, it will rise if your temp goes up,
as it should. Years ago, the manufacturers used to imprint the temp on the
sender, they dont anymore, so were all left guessing which one is right.
Hope this helps.