Is your QuardaTrac misbehaving at present? If not, I'd suggest keeping it, as long as you don't intend to do any heavy duty rock climbing. Granted, the QuadraTrac isn't nearly as strong as a Dana 20 or a Dana 300 t-case, but I've seen plenty of them work fine as long as they are serviced properly and not overly abused.

All CJ7 differentials are offset to at least a small degree. I have a Dana 300 transfer case, which is considered a centered rear output. And yet, the differential in the AMC 20 rear axle is slightly offset -- by that, i mean that the two axle shafts are different lengths.

CJ7 axles that were mated with a QuardaTrac T-case are even more offset, clearly to the point where it is observable without measuring.

1977 CJ-7, fiberglass body, AMC 360 w/ headers, DUI ignition, Edelbrock intake and Holley 4150 carb, TF999, Dana 300, 4.56 gears lockers, York air comp, 4" susp lift, 2" body lift, BFG 35" M-T tires, Megashifter, AGR pump & box, REP8000 winch.