What I can tell you is that the Cummins installed sensor ; that reports engine temperatures to the ECM; is beside the thermostat housing. ( upper rad hose connection) What I can't tell you is if Alpine uses info from that sensor for dash gauge operation. There are several other spots on that side of the cylinder head , between the valve cover and exhaust manifold, where a manufacturer could install another sensor.
I have this document on the, injector pump side of the CAPS era C engine, but have been unable to locate the same image showing the other side of the motor, that would pinpoint the coolant temperature sensor.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.