I have never had a manual sunroof apart, but the electric ones use a motor in the trunk with a long screw driven device to activate the roof.

I would suggest trying to find a blow-up on-line of the inner workings of each. The 'Catalog of Illustrations' should show all the parts needed for both versions.

I do know the US cars all had the electric version except for the 123 wagon and that was only because Mercedes could not figure out where to put the drive motor, so there should be a description of each type in the Catalog.