Midlife is correct about the two wire. I did find more than a couple but thru no fault of anyone but myself, I broke a socket/wire and needed to find a replacement to avoid things being only "half-arsed".
Somewhere here, in all the posts on the subject, someone directed me to the socket and I found them at one of the standard parts stores, I just can't remember which. It very well may have been midlife. Then again, a good number of the logerterm members have been more than a little helpful with a plethora of things.
I also figured, and mentioned in a post I couldn't find, I was surprised to see they were actually labeled for the Maverick and or Pinto of the same era.
In the end, I took advantage of the 3rd wire and made it functional like the actual turn signals on the '73. The reasoning was the added feature for safety as a sort of DRL with a higher mounted, secondary turn signal, again for safety.
There are too many drivers that lose sight of the road from distractions and while our older cars can be "eye-catching", many times they're not and wrecks happen. Anything to help mitigate or better yet, eliminate, the worst from happening.