Trying to work out in my head how there can be lateral movement in the donut if the spigot bush is functioning as it should and the donut is in tact.
I have eyeballed the donut and it appears fine yet there are obvious marks on the inside of the bell housing and on the outer surfaces of the donut to indicate contact.
Suggestions?
Floppy, sloppy, loose, torn gearbox (or engine) mount?
As Craig said, your mounts are allowing too much movement of the driveline. Probably on startup or shutdown, or possibly gear changes.
..."spigot bush is functioning as it should and the donut is in tact".. none of that tells me that the spigot locating bearing is not substantially worn or that there is not too much clearance in the flywheel receptor. Borderline possibility.
Failing that, your rear engine mount could be completely flogged out and it is doing a lateral move under torque reaction say as would arise from a standing start. It would have to move an awful lot for it to cause the contact and you would be noticing other issues as well.
Do you have the correct combination of rear engine mount and Guibo size ?
Just for the sake of it ...
It was the front donut. Major split!
Vibrations then snapped the spigot bush shaft causing the propshaft to swing around inside the bell housing.