ok so im getting ready to go all new! i just finished building my ls6 motor for my 91z and i want all new wiring. im going to order the engine harness from speartech and i was womndering if that harness had everything like accessory and lights and interior things....etc? or is there a seperate harness i need to control my headlights/brakes, guages...etc?

basically this is what i changed; went from a 91Z with power options except pw seats and mirrors to the same car but no more a/c, no more pw windows or locks, no more stereo, no emission stuff of course, and no more windshield wipers. ive also made my own complete guage panel with autometer guages which isnt yet installed cause i want to rip out all my old wires and start new. i have the ls6 and t56 and a pcm just need a wiring harness(s)

 

anyone?? let me simplify, are all the electronics in a 3rd gen controlled by one harness or two? lsx one harness or two?