Starting in the mid to late 60s, American imported Alfas were required to have four-way hazard flashers. European versions of Alfa Romeos where not required to have four-way hazard installed until much later. My1972 Giulia did not include them so with several long road trips upcoming it is prudent to install a flasher kit. 
This Hella hazard warning kit is a great looking and an easy system to install on Alfas without hazard warning lights. The red pull knob also flashes and the unit makes a very audible sound. When installing this hazard kit, its a good time to upgrade your turn flasher relay to one that works with LED bulbs to avoid “hyper flash” due to using lower voltage LED bulbs.
Wiring the system.
R: Right turn signal wire after turn switch
L: Left turn signal wire after turn switch
30: The power that used to supply the flasher relay
15: Switch power from the ignition switch (if you want turn signals NOT to work with the key off) or always on power that used to supply the flasher relay
49s: Power in on the flasher relay (pin 49 on flasher)
31: Ground
I have a similar hella switch but there is no 31 ( ground) plug in.. It made me puzzle on how did it turn the built-in indicator light on, well it does seems to work without by some resistance magic.. no ground at all. Thanks for sharing !