This is quite nifty in terms of packaging and weight, vs. the planetary gear set that Audi used on the dual range 01E, which adds ~8" to the tail housing of the transmission. It is also just slightly better that the ratio used by Audi (1.59 vs 1.54). This is certainly worth investigating more.
Also, I double checked and the automatic transmission from the A4 has basically the same torsen center differential as the 01a that is in the CQ. The difference is that on the B5 they ditched the locking rear differential and instead used open front and rear differentials. The B5 system relies on a system which monitors individual wheel speed and applies brake to spinning wheels to divert torque to the other wheels which have more traction. In other words, if you are driving a b5 in the mud and your ABS system/wheel speed sensors aren't working correctly you could easily spin just one wheel.
By keeping my locking rear differential in the CQ, the quattro system will be identical with the auto trans to what it is now with the stock 01a manual transmission (for better or worse). Now, since I still have an open front differential, it is still possible (though less likely) that I could get stuck with one wheel in the air spinning and very little torque applied to the other 3 wheels. To avoid 100% avoid that I would need either:
1) a locking center differential
2) a locking front differential
3) a way to apply brake pressure to individual front wheels on command
4) probably a number of other ways to do this that I haven't thought of
I kind of like the idea of trying to adapt a locking center differential from a 4kq in place of the torsen on an auto trans... but that will be more of a long-term science project
