We finally used a front propshaft modified at the rear.
No vibrations, no problems, this one propshaft works very well, we are very happy with this mod.
We had the gearbox and transfer case completely reconditioned, no short cuts, this photo shows the double cardan joint.
Note, to be able to fit a front propshaft to the rear, you have to use a front output flange, the std rear output is too small for the front propshaft, thus we were lucky we have spare to use.
Note The American flag in the background and the OME shocks.

Just a Toyota Hilux 4x4 with a few mods, nothing too extreme.