well most of the people here that would try a mod like this already have a diff locking device, and it just wouldnt work with one..... If you need to turn sharper i still dont think it would help you much.....
try taking a toy truck, holding one wheel in the rear and rotating the other, it does pivot on the axis, but with lateral drag on the front tires with a PU that doesn't have good weight distribution (or even a runner which has a heavier rear) isnt going to make much of a difference it will prob just drag that tire.....NOW if you do a front digg and take the whole rear axle out of the drive equation it seems to me this may help a bit as the other rear tire is not trying to push the axle your trying to drag....
like i said however this is just my opinion and i just dont see it feasible to go threw all the work, especially since the pulley system alone wouldn't be worth the work IMHO would be way easier to plum a cutting brake in and use the factory hydraulics...
