The cross member on the 120 is the same regardless of the box the car left the factory with, M30, M40 or M41.

As Matt pointed out there are two sizes of output flange.

The method I use for dropping the box is to split it from the bell housing, undo the 4 allen bolts. I use a Snap On allen key with a ball ground on the end. It allows you to attack the allen bolt from an angle. I just lift the box down lying on my back with the car up on stands.

I put it back the same way. I lift the front of the box up so it is standing at an angle up against the bell housing, with the input shaft in line with the release bearing. I then just heave it into place.

Personally if I didn't want to lift it I'd make a little cradle for a trolley jack and do it that way.

As ever be safe, I have the scar on my head to prove these boxes can bite. On the positive side the nurse was pretty.

Regards

Pete