This harness is designed for 1996-200 Vortec 7.4 big block engines with a 4L80E transmission. These engines were found in certain 1996-2000 Chevrolet or GMC full-size trucks. Included with this harness is an 8 circuit modular fuse block and GM 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. This harness also requires the following mating parts; ECM #16229684 or 16244210 from 1996 or 1997 models. We recommend checking the online manual for the full list of required mating parts prior to ordering. 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.