S-Belt on ML-430

Has anyone replaced the Serpentine Belt on an ML-430.  I just replaced the one on my e-320 and it was a piece of cake after I found the tensioner (with a little advice from anohter forum reader!)  Which one is the tensioner on the 430?  I can't believe the dealer wants ~$100 to do this job...the belt was $14.95!!! Paul37999.9705208333

Thanks for all the help...anyway:  It was really easy, just needed a TORX socket set (I think it was the E12 size that finally fit) to release the tension on the automatic tensioner which is the pulley in almost the center of the engine.  Easy job, took about 5 mins once I found the right size TORX socket.