Re: aftermarket power distribution (relays)
you can always run a larger wire to a dist pannel then tap off that.
each can have its own feed, fuse etc. there was a new product in one of the diesel mags not too long ago dealing this very problem , basically it was a small box or series of boxes that distributed power but was suppose to use far less wiring. have a look at some boat shops etc, they have hundreds of different sub pannels, distribution blocks etc.
Early 99 f350 4x4 crew cab, auto. pmt2 pcm
2001 cup holder ,T500, MAX AC ASSIST AC mod, Diy Twin tymar, TS chip, Powerslots & Hawk pads, ford AIC, ..... with big fat want to list.