The order from bottom to top for a w126 is:
Bump stop
Flat plate (sitting on the snap ring on the shock)
Protective boot
Rubber bushing
Fender
Rubber bushing
Concave up metal plate
Nut

Both the plates are highly necessary. Re-use the old ones if they didn't come with the shocks.

EDIT: Just realized you said 300D, not 300SD. Different chassis from what I know, so don't take my word on it.