1. The BW1339 QT has a bad rap... but alot of it has to do with improper maintenance...most didn't use the QT FLUID in the case which destroys the center diff and brakecones.
I LOVED my QT with fulltime use...even for a chain driven case it is a very dependable case if properly maintained. Chains for the QT's are around $125 and not too bad to change...
2. All fronts were open and most rears.. some opted for LSD. Since the QT had its own differential, it was imperative to have and open diff up front to maintain steering control since its a full time case. Part time conversion kits are made by MileMarker for around $450 to conversion to Part time which allows you to install a LSD or locker up front.
3. Prts for the QT are not that easy to find... except for gaskets, seals and bearings. The center diff housings were never made to be 'rebuilt' and no parts are available to replace the internals of the center diffs of the QT.. HOWEVER... http://www.willys.net/html/transfer_case.html
has rebuilt QT center diffs.
*** since the axles diffs were OPEN and the QT center diff works as and OPEN diff...the QT would transfer power to the AXLE with the LEAST traction... so if you spun a front wheel, the QT transferred power to the front axle... this is when E-Drive would be a nessecity. I used E-drive as soon as I left pavement.
4. The E-drive switch in the glove box does just that... it locks the front and rear axle together for a 50/50 torque split with 100%lock. IT takes the QT center diff out of the equation.... It is intended for soft surface roads only.. driving in E-drive on hard roads can damage the QT unit.
any other questions, just ask....