Where to find switch for hazard flashers?

[rgunlock]

My wife and I had a breakdown in a bad spot on the interstate at night with no hazard flashers. Best I could do was leave a turn signal blinking. Needless to say, she doesn't want to do another roadtrip until that is fixed.

I'm assuming the problem is the switch. This is the one on the right side of the column down near the dash. I believe it is supposed to stay out when you pull it, but mine doesn't. Any case, I'm not having much luck finding one. Anybody know who sells one? This is for my 78 GMC K15.

Thanks!