I'm working on this very same thing with one of my old Ford trucks right now, and Word to The Wise: If you need to actually hear the unit, don't leave the new one dangling under the dash, and/or zip tied to existing wires, as they need to be mounted on something metal in order for the "click" sound to resonate (is that the word I want?). The one in my truck looks almost exactly like yours, but I haven't looked for an OEM (square) replacement, as I'm not concerned with keeping this 100% original, so if you're like me and you install a 552 or 536 flasher/unit, you'll need to figure out a way/place to mount it.