I've done only one install on this car, and it was so long ago I'm afraid I can't remember anything special about it. I'm sure that was a good thing, because if it was a difficult install I would remember it.
Feel free to give the guys at grease car a call, I'm sure they have more info on installing kits on this year model.
http://www.greasecar.com/products/greasecar-auto-kits/mercedes-sedan-1995-1999
P.S. If you go with greasecar, get the co-pilot. Wouldn't drive without it. Great over all product.
Good luck.
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Professional greasecar installer
Austin TX
98 Jetta TDI with grease car kit + veg-therm (totaled)
87 MB 300SDL running on B99 / greasecar kit + 30 fphe
www.austingreaseguys.com