Holley EFI LS main harnesses have a MAP sensor connecter designed for use with an LS1/2 style MAP sensor. The 558-416 is an adapter harness that can be used to adapt any LS harness that uses an LS1/2 MAP sensor connection to an LS3 MAP. Also great for use with LS Hi-Ram intakes that require an LS3 MAP sensor. Convert LS1/LS2 Map Sensor to LS3 Sensor, Chevrolet V8.