Oak,

Just finished my project of replacing the tensioner tonight. Wow, what a learning curve. It took me way too many days and 2 different parts orders. I could now go back out to the driveway and do the project in under 2 hours. I used the MB manuals for the the 124, the MB WIS discs and researched several discussion groups. By far the best analysis was provided by DUKE2.6 in this forum back in July 2005. I originally found his posts by typing in TENSIONER inthe search field. That search will also provide you with several pictures that aided my project. The first link gives a good overall perspective and the second is a step-by-step to replace:

http://www.peachparts.com/shopforum/showthread.php?t=129793


http://www.peachparts.com/shopforum/showthread.php?t=129491


The thing that gave me the most fits was that I was trying to use a tensioner that was busted. All my issues went away after I purchased all new parts (tensioner, adj rod, dampner shock). I would recommend replacing if your car has miles on it. I would also recommend removing the Y bracket entirely and sealing that bolt that goes in the lower timing chain cover. The last thing you want is an oil leak down there.

Good Luck,

Mark