Where is the coolant temperature sensor on a 1991 12 valve cummins?

On a 1991 12-valve Cummins engine, the coolant temperature sensor is located on the engine block, near the thermostat housing. It is typically found on the driver's side of the engine, towards the rear, and is screwed into the block. This sensor monitors the engine's coolant temperature and sends the information to the engine control unit or gauge.