Yeah, lots of Franken-Broncos running around these days. Lots of rust led to lots of swaps of just about everything.
If the dash has light-bars underneath the controls, then it's approximately a '73 or newer dash. With the hazard switch there (assuming it's a factory install), then it's only up to a mid-'74 dash. Since you do not have the switch on the column, then I'd say it's limited to up to very early '74, or maybe late-'73.
For a short time during the transition in '74, Ford actually installed hazard switches both on the column and the dash. Typical Bronco yearly transition stuff.
Do you know where the frame VIN's are located? I only remember the one on the passenger side front, near the charcoal canister (is that still there?), but there are either one or two more scattered around the frame.
I'd normally say just grind off the coating near the spot you think it might be, but those numbers are very often extremely shallow stampings, and might wipe right off if you get too aggressive with the grinder.
And speaking of Franken-Broncos, maybe a few other things to look for. For instance, a '76 would have had disc brakes in the front, a proportioning valve on the frame (instead of the simple H-block), and the "inverted-Y" steering linkage.
Would also have had a slightly different parking brake setup.
Oh, and on that year model too, the charcoal canister would have been moved up to the firewall on the passenger side. Not the tin-can style that was mounted to the frame on mid-'70 to '75 models.
Good luck. Post up some pics when you get a chance. If you're not familiar with those things we've been talking about, we can verify at least some of them visually with pics.
You can't post up directly to the forum unless you become a contributor for 12 bucks a year. But you can still put them online using other image hosting sites, and then link them here for use to peruse.
Thanks. Good luck with the hunt for info.
Paul