Drag only Gears are much softer to absorb launch Impact as said above, they aren't recommended for Street use.
Did you figure out what was wrong with the Yukon gears? Pinion Wobble?
I have a set of Visteon 3.90 gears, I bought a while back, came out of one of Dale Jr.'s DEI cars. They have the Remedd treatment, look about like Chrome/Polished, very nice quality.
I'm not going to use them, PM if interested.