Mercedes: 1999 E320 fuel pump replacment, differential pressure, 420sel

Question
I have the pump, where is the old external pump located? which side on? any hints on replacing the pump myself?  

Answer
Randy,
Look on the passenger side between the axle and the fuel tank. That is the location on my 420sel.
My vehicle actually has two pumps at that location. Some vehicles have an internal pump only. Some vehicles have an internal and an external pump.

Just the usual cautions about taking the battery ground off before beginning removal, and, the use of jack stands or a proper lift to raise the vehicle. Use care in loosening the line connections. They may be still under pressure and you could get a gasoline bath or worse in you eyse.
You may need to run the tank empty before starting the job. Or you may need to place a golf tee in the line to keep the tank from draining under differential pressure.
Additional info may be available at benzworld.org/forums.
Good Luck
Rob