Wow, I have had dim head lights on my truck since I got it going. I had no idea why. Next time I work on it, I am going to go over the complete ground system for the head lights. T hank's very noligabile HAMB crew.
For much brighter tail, brake, park lamps, after adding ground wires, remove the lenses and scrub them inside and out with soap and water. Scrub and scuff the inside of the housings then mask off the sockets and paint the inside rattle can gloss white enamel. Let dry completely. Reassemble with new, if possible, gaskets and bulbs. If 12V use 2357 bulbs which have a much brighter stop/turn filament. Put on your sunglasses when you have somebody hit the brakes to check 'em!
All very good advice given. Bad grounds are nothing but a pain in the butt. I just finished completely rewiring my 54 Ford by making my own harness. With new wire, new bulbs, new grounds, cables, cleaned every connection on reg. and switches and such, and even though I stayed with the 6 volt positive ground, I think I have lights every bit as good and bright as a 12 volt system. Also I think the peace of mind in knowing the wiring is in top shape is worth the effort too. Smokey