My 99 ML320 is due for A Service and I want to take it to my trusted indy. What exactly is addressed in A Service? What is B Service?

The truck now has 116,000 miles on it. I don't have the owners manual with me at the moment and I will certainly look for recommended service intervals when I get home. But in addition to what the manual recommends, what other items should I have inspected / replaced.

I tried the search function of this great site, but came up empty.

Thanks in advance.