Finally changed the gearbox last weekend and upgraded to an F20. General opinion all round was that the F16 would last about a week, 3 months later it was still working but it had started to sound like it was straight cut. The diffs got plenty of slack in it now anyway. It was thoroughly tested with 215x17 rubber and a heavy old V6 stuck on the end of it, treatment at times was far from gentle.
At one point it was filled to the top to quieten it down, it worked too, the box simply found its own level by forcing the excess fluid out.
Gearing in the F20 is a definate improvement while not being too low. Definately an added factor. Cant wait to kill this one and drop the F28 in.