Good Day. After installing my gauge cluster and new oil sending unit, found that the oil pressure gauge goes all the way to right on start up then drops of once engine warms. But it still reads past half to the right. Replaced the sending unit thinking it was at fault. Still the same. Anyone else have this problem. Thanks.

Oil pressure always drops when the oil gets to working temperature.
It also depends a bit on what kind of oil you use.

How's you fueltank meter reading ?
Is it spot-on with a full tank ?
I've found that most dashboard voltage regulators don't give the right voltage pulse.
My fueltank meter always reads 3/4 full with a full tank after I change the dash regulator.
This also give lower oil-pressure and lower water temperature.