I just flushed my coolant on my 2000 a6 2.8 Quattro. The heater hose by the battery got really swollen. I want to replace both heater core hoses. I can't see where they connect to the engine. Has any one replaced these hoses?

 

I haven't replaced them, but one connects to the rear main line, and the second one (still in the back of the engine) to the line that goes to the water pump housing.
Probably you'll have to take off the airbox/manifold/throttle body to have a good access to the connecting points.

 

Maybe this helps better ;

 

Is there any way to clean my heater core? I wanted to disconnect the hoses in the firewall and then attach a 5ft hose on each connection. Then attach a water hose to one of the hoses to flush that junk out.