I just did the WP on my 123, and saw a variety of pumps to select. I purchased a Graf, Laso, also a good choice. It has a cast impeller, with swept back blades. Less cavitation, better design. AZ, and other chains had stamped straight blades, and so I stayed clear.

The Graf matched the OEM. I filled/drove 3X to get a filled system.

Good Luck,

__________________
Gary
Experience is something you get, Just after you needed it....
'99 E300 295K, '83 300D 220K, '75 240D 185K sold
'80 MCI Bus Conv DD 6V92TA, w/4 cyl. Kubota diesel GenSet 12.5KW