There are a variety of ways you can add turn signals to your WW2 jeep. My favorite involves hiding them in the front marker lights and behind the rear reflectors. My next favorite method is to incorporate them into rear brakelights if you have one on each side (swapping out the passenger side blackout for another brakelight).
A customer recently wanted an entirely different design so we set out and came up with another style of turn signal, this will work only on WW2 Jeeps converted to 12 volts.
The parts we used were a standard 8 wire turn signal switch available from places like Walcks 4wd, bullet style motorcycle led turn signals that we found on ebay, and an led compatible flasher relay purchased from Napa. Make sure to ask for the flasher relay I photographed, standard flasher relays will not work with LED lights as LED do not draw enough current.
Wiring incorporated vintage style reproduction cotton wire where it would be visible, and standard modern wiring underneath and in areas not seen. All connections were soldered and sealed with heat shrink tubing. Alot of this is available at almost any auto parts store.
The creation and installation of the system was simple but took a few hours. With the turn signal switch comes a basic set of instructions that show you where all the wires and the fuse connect. You need only to find a 12 volt source to connect to (like on the ignition switch) and the rest of the wiring is independent of anything else on the Jeep.
The nice thing about the motorcycle lights is their wiring runs through their threaded base, so once you drill mounting holes these lights are easily attached without having to make any brackets.
In the end the most difficult parts of this design were finding the right flasher relay and seeking out LED signal lights that looked vintage (ebay is the only place I can find these). After that it was alot of soldering and running wire and voila, an unobtrusive turn signal system made from modern items. This is a system simple enough for most folks to be able to install without any particular level of inventiveness required.