Unfortunately you have to know what the engine came out of to get the correct tab.
Usually there are screw holes you can find to gauge which pointer your particular engine needs. But they can be hard to see. Maybe a pic of the front cover area will help someone here "point" you in the right direction.
All Early Broncos got the same one of course, but with so many engines from different Fords swapped in over the years it's hard to tell sometimes. And unless you're the original (or long-time) owner you can't guarantee it wasn't swapped out at some point.
Oh, and to add insult to injury, if the harmonic damper has ever been replaced there is a better than average chance it's the wrong one too. Ford used at least two or three versions with the timing marks at different points on the ring and the aftermarket manufacturers didn't take too much trouble to get the right ones in the right box. And then there are simply the mistakes at the parts stores where the wrong one goes in a box and does not get re-marked.
So JAFO's idea of making your own marks might be what you end up doing. No matter what pointer you get.
For comparison in case you haven't seen one before, here is a stock original style Bronco pointer:
https://www.wildhorses4x4.com/product/Timing_Marker/Bronco_Timing_Chain_Cover
If your water pump has the inlet facing the passenger side, look for a pair of holes that look about like they'd fit this pointer on the driver's side of the cover just above the damper ring. Like he said, at about the 2:00 location.
If your pump's inlet is on the driver's side however, all bets are off and you have to use a car or universal pointer. Or make your own.
Paul