When i removed my temp.sender from the head i installed a short nipple and a 'T' fitting to accomadate the oem unit and the aftermarket unit.Why does the factory gauge show a lower temp now?Does the sender have to be into the cyl.head to give a proper reading.The after market gauge also reads about the same as the oem.Also is there another location for the sender so i can keep both gauges?

Temperature probe tip(s) must be inserted into an area of coolant flow inside the water jacket to read correct temperature...................

These heads are interchangeable driver's and passenger's sides. So where you have the stock probe you could move the new probe to the other head's opposite end. It should have a threaded plug you can remove.

Thank's Lupey6.5,i will check that out when i get time.That is supposed to be the hot side of the engine but it is also a crowded part of the engine/engine compartment too.