Are you plagued by crummy electrical connections? The original wiring harnesses were very good with WeatherPack connectors common. But any splicing usually allows corrosion to muck things up. I like to use marine grade connections like Ancor's glue filled/shrinkwrap connectors. Otherwise I use lots of Liquid Electric Tape which is a liquid neoprene that seals out moisture. My routine is to do this- solder, seal, shrinkwrap, seal again, wrap with electrical tape, seal again. I never have corroded connections on a car or boat using this method. I have even spliced battery cables by stripping back 1/4" of insulation, inserting the ends into a short length of same size copper tubing and butting them up, drilling two tiny holes in each side, and using a blowtorch to get it hot and feed solder into the tiny holes until the tubing/cables are solid. Be sure to polish the copper strands and the inside of the tubing, just like sweating copper pipes for plumbing. I then continue with the seal, shrinkwrap, seal, tape, seal routine. No voltage drop and no corrosion.