wow, how did you polish all the things up so well >?

I'm not the OP, but I've been polishing out the valve cover on my OM617 and it's coming out alright. I sanded with 400 grit, then 800 grit, then polish with brown rouge and a fairly aggressive polishing wheel on my drill. I do a few heavy passes, then a light pass with the aggressive polishing wheel, then finish it up with a microfiber and metal polish.

It looks pretty good so far.

I sanded the smooth aluminum parts with sandpaper starting around 600 grit and then working my way up to finer grit and then using Blue Magic aluminum polish. The coarse aluminum parts got cleaned with oven cleaner and then scrubbed with Blue Magic aluminum polish and a wire brush. Yellow zinc parts can be soaked in Evapo-Rust for a very short time if they are rusty (it removes the plating if left in more than a few minutes) and lightly polished.

Is there a difference of engine mount arms on the w115 617 vs 616?