So when I say 3" its only on the passenger side front at this point.
I am in the process of completing the entire suspension lift and haven't yet put the back leaf springs on.
When I say 3" i mean the difference between the drivers side radius are and the passenger side radius arm.
Ok, so let's call this a "misalignment" or a "discrepancy" then, because it's not a "lean" until it's all put together and the body is leaning.
But since you're not talking about the whole Bronco at this point, you don't need to worry about the body mounts being part of the equation yet either.
When it comes down to the final setup though, don't go by visual cues, or even measurements if they involve the body unless the body mounts are equal height all the way around.
The entire front diff is disconnected and I am trying to connect the radius arms with it unattached.
So you are basically doing the initial setup while watching the radius arm tips vs the ground. With 3" you have an issue. Either a bushing is in wrong, as suggested (and this does happen a
LOT and to a
LOT of us still), or your axle tubes have spun, or your front end was put together incorrectly from the factory.
All of the above are possibilities. And if more than one, then you're dealing with stacked-tolerances and won't be able to get it aligned the normal ways.
So first, what year is your Bronco, and more importantly, what model front diff? If it's a Dana 30 from an earlier model, then the spun tube(s) are a distinct possibility.
The "cure" for this is to quadruple check that the C-bushings are installed correctly, all four oriented to their proper positions to tilt the differential back and down, and then literally stand on the one of the radius arms and try to spin the tube in the center section.
Which one is the "correct arm" however depends on your axle. Yes, you must stand on the high-side obviously or it won't work, but depending on which one benefits you the most, you may have to flip the assembly over so you can stand on the opposite arm to accomplish your goal.
Either way will get you level, but which one is best depends on your pinion angle.
Once both arms are level, you need to tack weld the tubes in place. Just a tack, so that if you find you need to change alignment later to correct for one thing or another, you still can.
Then, once the rig is on the road and dialed in, you can fully weld the tubes.
All this of course, only if the tubes are the problem. But it's a very good possibility when you're that far off.
Paul