Hi Jim,
I wish I could help you with the part numbers. I used to have these shocks on my 190E which I sadly had to get rid of several years ago. You might be able to get the part numbers for the 500E off of TireRack, I think they sell them.
Regarding the color I'm 100% sure mine were orange. They stood out like a soar thumb before I lowered the car.
Good luck with your search. BTW are you looking to stiffen up your ride? If so why not try the AMG Shocks, although I'm not sure if they are still available.