Check ebay for "turn signal switch"-- throw in "vintage" for old ones. I have a vintage Signal Stat 400 in my '53 3/4 ton, and a Yankee (700?) in my '47 Hudson. You can get a nice new one for under $30; I just picked up one of these for the '46 Chevy Aerosedan I'm building:
https://www.ebay.com/itm/334344925599?hash=item4dd882b19f:g:6qMAAOSwTcxggO~E
So, there is a ton of options regarding switching. Some of the switches are 4 wire (2 wires from flasher in, 2 wires out to left & right side signals), and some are 7 wire (2 in from flasher, 1 to stop/brake switch, and one to each light). If you find a vintage switch you can just google up the wiring diagram for it based on model number; if you buy a new one it should come with wiring instructions. Most guys will put the front signals into the parking lamps mounted on the grille (what I did on my '53 3600); as for the rear signals it will partly depend on what kind of switch you get. 4-wire switches require an extra bulb in the rear lamps, whereas 7-wire switches will have the existing brake lights double as the signals.
