What are the symptoms of the failures?
Are you confident they have been the correct gearboxes for that engine type? Silly question - Is it possible the lower spec might have been fitted?
I'd also consider the flywheel as a potential cause. It could be sending judder/vibrations through the input shaft of the box.
when u put the foot down then once u let it off it makes a knocking noise from drivers side.
on the passanger side it vibrates above 60. ( not a loose whell or egg in tyre nor is it un-ballanced although may be susension)
jacked up front end and spun the wheels to discover a metal rubbing and banging noise
