When mine went on my '87 300D, I first replaced just the pulley. About a month later, the whole thing broke loose again. The second go around, I replaced the shock, spring, pivot arm, and pulley. As far as the configuration for the belt...that is one that someone else will have to help with as I do not own this car any longer.

__________________
Mike

'80 300D
'84 300D
'85 300D
'87 300D