Turn Signal Quandries

[jaywashburn]

Fellow members, seeking advise about how to resolve a current electrical that has me a bit flustered. Recently became owner of a '75 K10. For the most part things are pretty sorted out on the vehicle (runs, drives). All of the electrical components operate as they should. I went through & cleaned/replaced all ground straps, fuses, & bulbs on truck.
The one thing I noticed was the hazzard switch knob on steering column was broken off so I ordered a new turn signal switch & knob from a local auto parts store.
Everything on the new switch looked identical to old one except the harmonica plug (it wouldn't mesh with original female counterpart). So, I de-pinned new plug & re-pinned to original plug. After that everything went back together fine.
Upon start up I notice that when I go to use the turn signals (left or right) my hazzard lights come on @ all 4 corners (?).
I checked on the LMC site & they show there are 3 different turn signal switches made for the square bodies (73-76, 77-83, & 84-87). My question is could I have the wrong TS for my era truck ? Is that why I have the errant response when I use my turn signals ?
TIA for any input on this matter !