4. The LS-3 is then flipped right-side-up once again, so that the S&P oil pressure sending until adapter can be installed at the rear of the block. This is adapter has three ports: a 16mm male, 16mm female, and 1/8-inch npt port. The metric ports thread into the block and to a sensor for the computer and the npt port makes it possible to run the factory oil pressure gauge. It's a necessary and trick piece.