I have a '99 ML320 73K miles. I purchased the truck in '00, not original owner.

At 60K I went through the same issue, I asked for fuel filter replacement.

They came back with the same answer and a quote of $750. I told them I will ask again, all I need is the fuel filter replaced, I have no problems with my fuel pump system, if the filter I need is not available, then I don't think it is my problem.

If the design is changed and the filter new filter do not work with the current system, they must have available the original part for a number of years by law. If the part is not available at all because a design change, then there may be a flaw in the original design and must be replaced for free. Specially when it is not just one part, but almost the whole system. This is almost like saying, the oil filter design changed, the new one do not fit in your engine, and the old one is not available, so you need a new engine!!! This is definitely against the law of marketing practice.

They said that ahhhh!, so you don't have a problem with your fuel pump system? So now we understand, all you need is the filter replaced at 60K. I said EXACTLY.

The whole system was replaced for free, as the receipt says, pump, aux pump, filter and hoses.

Just my story, hope it helps.

Rene