I assume the old engine is the '85. What year is the new engine?

If it is indeed the old one was an '85, I recall there are two sensors on the block one between #1 and #2 glow plugs and the 2nd located between the #2 and #3 glow plugs. The first one is for the EGR computer and the second one is for the temperature gauge. But you are saying there are two on the Thermostat housing? I know that one on the housing is a temperature switch.

The new engine depends on what year it is. If pre '84, again I recall there is only the temp switch on the thermostat housing and the temperature sensor for the temp gauge located between the #2 and #3 glow plugs. The temp gauge wiring is intertwined with the glow plug wiring.

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1983 123.133 California
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