An oil pressure switch indicates the presence of oil pressure above a certain point. They display oil pressure in the middle of gauge as long as you have more than 6 or 10 psi - like most dummy gauge Fords. Switches only have a single wire.

An oil pressure sending unit will have 2 or more commonly 3 wires and actually measure the oil pressure and report it to the gauge. LS1s use an oil pressure sending unit. Most people have no idea of the difference, or even that a difference exists, and that certainly includes parts counter help (idiots) at the large chain stores.

Teflon tape is not needed. The sending unit uses both a tapered seat and thread. As long as it is torqued properly, it will not leak.

No DTCs will be set from a oil pressure sending unit failure or replacement. You can however set a DTC if you forget to reconnect something during the intake manifold install.