Tollmtn, It sounds like I could get away with nothing, but the 2 inch spacer would help. I would like to dial in the pinion t case flange angle. Those adjustable A-Arms are pricey. I don't understand fully what an adjustable lower control arm would do. I thought it was just to re-center the wheel. Would the adj. LCA help with the t case flange angle? Thank you very much by the way.
This is why and how Adjustable LCAs help, this requires some thought. When stock a WJ A arm is above horizontal with the frame the UCAs are below horizontal with the frame. If you drew a vertical line just touching the end of the A arm as you add lift the arm will swing a radius pivoting down on it's mounting point. When the A arm reaches the point that it is horizontal it would extend past the vertical line toward the rear of the Jeep, it will pivot down a few more inches with 3" of lift. Then if you put in a two inch spacer it pivots back up and will be up to virtually horizontal and at it's most rearward point of it's arc.
The LCAs start out below horizontal so if you drew a vertical line just touching the end of them they would move away from the line right from the start but in the opposite direction
they move toward the front of the wheel well.
So in affect the upper arm as it pivoted down to horizontal moved the top of the diff toward the rear, (this happens with lifts up to about 3.5 " when you use a 2" spacer). Meanwhile the LCA started out below horizontal so as it pivots down it moves the bottom of the diff toward the front of the wheel well. As you see, the top of the diff moves back, the bottom forward, this rotates the diff pinion up.
SOOOO! If you have adjustable LCAs you can adjust them longer to center the wheel in the wheel well but that also rotates the diff and corrects the flange angle you just have to balance the two out. Also you can see why a stock length A arm like IRO's will not have adjustment in the right direction for the rotation you need.
For reference. When I had 4" of lift, the OEM A arm with a 2" spacer and stock LCA my A arm was just 2 degrees below horizontal but the LCAs were at 18 degrees below horizontal. That made my pinion and T case flanges 4 degree out, yours will be less. Even at that I did not have noticeable vibrations so at three inches you should be fine.
One other point, when you add a spacer it definitely puts the rubber bushings in a good position, that has been established. It also puts the ball joint about in the center of it's angular travel. From ramp testing I did with 4" of lift, the OEM arm with 2" spacer give you all the flex possible with short arms. The ball joint will not limit out with the rear sway bar disconnected and one wheel stuffed and the other in full droop. I didn't test this but I believe even at 3" without a spacer the ball joint will limit out or be dangerously close to limiting out.