Excessive transmission noise in car.

[Reckless Rat]

Have you tried the screwdriver stethoscope method to determine where the noise is coming from? If you get someone else to drive the car, use a big screwdriver and place it against various parts of the car's anatomy and shove the handle end in your ear. I suspect that it's the gearbox as the later synchro ones suffer from thrust wear on the layshaft which would be more evident on "drive" but reduced on over-run when the thrust is in the opposite direction.