Depends, but a normally running engine will have fluctuating oil pressures depending on engine speeds and loads. Generally speaking, as long as you have oil pressure, you're good, and at idle, good oil pressure is typically 35 psi or more, and 15 psi or more is acceptable for most engines.
Low oil pressure or fluctuating oil pressure.
Not enough oil.
It's to the right of the distributor.
Yes it has an oil pressure sending unit next to the distributor.
The oil pressure sending unit is on top of the engine at the back. It is right beside of the distributor.
rear main seal leaking
It is on the back of the engine, next to the distributor.
The oil pressure sensor is on the driver side front of the engine next to the oil filter.
Front driver side of the engine, just above the oil filter.
It is on the back of the block, just to the passenger side of the distributor.
On the block , Rear Passenger Side by Firewall , Left of the Distributor
You should change the oil in a Dodge Dakota every 3000 miles.