I have a 1999 430. Somewhere on this forum, someone suggested MB Roadside Assistance. We are way past warranty (130K) but they came out on a Friday night and replaced the battery, 3 year warranty, plus if I have battery trouble again, they will come out and replace no questions asked.

I think it was about $175, but I looked at getting a replacement from a parts store, it was generic, more expensive and I would have had to deal with it.

You can call them and they gave me a price before I agreed to have them replace.