I've had questions about a leaky injection pump on my 87 300SDL. One mechanic said he didn't have the speacial machine or tool, and would have to eyeball it, making marks of some kind. He said the job would take 3 hours ($330), and only involves 6 seals as parts.

The second mechanic I went to wants the car for the day, would charge $400 and replaces parts including fuel filters, which he insists must be done after this kind of fix.
Also important, he says, is properly torquing the screws or bolts upon sealing the pump.