This harness is standalone and is not intended to replace the OEM engine wiring.  Standalone harnesses are intended to run the designated engine & transmission only, generally when swapped into another vehicle. This harness is designed for the 1986-1995 Ford 5.0 car HO EFI engines. You must use the 1989-1993 MAF, Distributor, and ECM. 1986-1988 must add MAF (mass air flow) sensor. 1994-1995 must modify TPS wiring and change distributor. Harnesses do not include all the original connections for the original emissions. Included with this harness is an 8-circuit modular fuse block and Ford color coded wires with labels for easy installation. This standard length harness allows four feet from the back of the intake manifold to where the fuseblock and ECM mount. Perfect for those that plan to mount these components under the dash or in the glove box. We HIGHLY recommend checking the online manual for the full list of required mating parts prior to ordering.