All Classified forums require a Site Supporter subscription. It is only $25 per year and you can buy and sell whatever you like on the forum. To become a Site Supporter, go to Your Profile and select "Paid Subscriptions."
When I was a kid, both our 74 and 76 year model crews had the plain rocker switch. Our 1985 3/4 ton had the momentary switch. I had a 76 3/4 ton that also had a plain rocker switch, as does the 74 stepside I have now.
This is the switch that was mounted on my lower dash for fuel tank selection....and its not momentary it stays in either direction i put it in where as a momentary only stays as long as you hold it in the position.
See the pins for the bezel on the 73-74? That's how the metal dash has the holes for it. Your pic is hard to tell but if they aren't a match then someone swapped in that bezel. I just filled in the holes where mine was as I eliminated the dual tanks otherwise I'd post pix.