Have a look here: Comprising: installation kit for fuel pump. Fuel pump fuel line fuel pump fuel line fuel filter 4.2ltr. 1998 Audi A8 Quattro 4.2L # 4D0298087B

First part # is the pump.
Double check with dealer/supplier that is the correct one for your VIN and that it has not been superseded.

 

something I haven't seen mentioned is the fuel level sending unit. you need to remove it when doing the pump. also, it's best to drain as much gas from the tank as possible before doing this. when reinstalling the sending unit (driver side of the tank) be very careful not to get the float hung up on the hoses in the tank. I've seen this happen. when it happens, your gauge will say you have gas, when in fact your tank is empty. the engine will quit from lack of fuel, and most people automatically think the pump went bad again. when the problem is, your just out of gas...also, there is another fuel level sending unit in the fuel pump housing. I think it's for the low fuel level warning light, or maybe the computer that tells how many miles worth of gas are left. I've seen this re-assembled incorrectly. pay attention to these things and you'll have a good day.