Where to buy fuel return hose:
http://www.mercedesshop.com/shopforum/showthread.php?t=238219&highlight=Rabbit
This is from one of my past posts:
Volkswagen dealers also sell the injector retun hose as the older VW rabbits have similar injector bodies. It may be slightly cheaper to get it from them instead of mercedes. stocked under the VW number N 20 252 5 but Mercedes uses the same hose as well as many others who use Bosch Diesel injection systems.
If you need to fix it right now regular vacuum hose will last a 1 or 2 weeks before it gets eaten up and leaks again.
I used a piece of silicone vacuum hose on my Volvo diesel and it was on for a year with out leaks. However, when I took it off the hose was rock hard and had to be cut off and was no longer re-usable.