Brake Light Switch or Turn Signal Switch?
Below are from pages 8-150 and 8-151 of the 72 service manual
The very top one, white is switched brake power coming "from" your brake switch
Next one down, 18BR, means no 18 gauge wire, BRown goes to right rear stop/ turn
Next one down, 18DGN (Dark GreeN) goes to left rear stop / turn
Now look at the kick panel connector top photo. Terminal no 8 is BRown, is your right rear
Terminal no4 is Dark GreeN, the left rear