A 4-link system would have to exactly duplicate the geometry of the torque tube spring system to work at all. The lower link pivots would have to be placed exactly where the front spring pivots are on the frame, and the upper link would have to create a parallelogram so the rear end would travel exactly straight up and down. It would also have to have the same pivot points as the original rubber-bushed rear axle pivots. The only function the coilovers would serve would be to support the weight of the rear frame and the cargo box, and the shocks would probably have to be mounted exactly vertical to duplicate the operation of leaf springs. Bottom line- - - - -a successful 4 link/coilover setup would have to be engineered to do exactly the same thing the leaf spring system does. Why bother?
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!