Dave was kind enough to post pics showing the difference between the 603-015-00-01 and 603-015-06-01 front covers -

www.w124performance.com/images/OM603_timing_cover/timing_covers4.jpg

My EPC doesn't list a -04- front cover but that's what came on the 93 SD (attached pic). As far as I can tell, the difference between -04- and -06- is the -06- has a slightly bigger bulge between the vacuum pump cavity and tensioner attachment. The bigger bulge means immediately below the tensioner attachment is a fifth internal rib counting CCW from noon. At least I think the bulge is bigger. Maybe they squeezed in a rib without enlarging the bulge. I can't tell for sure from the pics.

Sixto
93 300SD

Attached Thumbnails