Getting thru the firewall took some time; went thru on driver's side. Forget going thru the grommet along with the factory 5/8" dia. harness. There's a small vacant recess (aprox 8mm) to the right of the main harness pass-thru. I punched it with an awl, sprayed some silicone on the hole and the cable and worked it through. Finding it and getting hold of it on the other side requires some patience. Once run to the passenger side of the engine, hook-ups went OK. Note: CYL setting should be set for 1-Cyl engine, not 8-Cyl, all 3-switches down, due to individual coil-packs. I did a better job of tieing in to the 12v switched source than they describe. I spliced, soldered and heat-shrinked a lead that comes back out of the fuse box. I mounted the light on the A-pillar. It looks pretty good, and the light is plenty bright.