I thought it only fair to share the rest of this saga, to date, as much as it pains me to tell it (and no it is not a need-a-new-upper-engine bad story but it has been a pain....) The advice on here varied in parts so I guess I can say I followed most of the recommendations. I chose a shop who serviced a 300sdl I recently bought according to the records; the guy I used to use retired. They had no problem with me using my own parts so I got an Iwis chain and MB upper guides and tensioner (all of which was about $500). Before they started they called and quoted $600 for labor, with a disclaimer that, given the age, there could be more for the unexpected (frozen bolt, etc). I said fine. They called back not long after and said the labor would actually be $2300. They mis-gauged it. I told them to put it back together as obviously they had no idea what the job done properly would entail. To their credit they didn't charge me. My small town is 90 miles from them so I had it towed to another primarily european car shop in that same area, who told me they could do the whole thing for $1060 plus tax, and I specifically asked if they'd use MB parts and they said yes (they said their warranty program would not let them use my parts). They did the job, seemingly all was ok, I drive it the 90 miles back home, and when I get to my driveway it is smoking like crazy and there is oil pooled around the front of the right valve cover. Oh, before leaving the shop I again confirmed MB parts were used as $133 for a MB tensioner seemed too cheap. He said "Oh I use a guy who has a lot of new old stock (ie that's how I can get MB that cheap)." Anyway, at least part of the oil problem turned out to be insufficiently tightened valve cover bolts but I now think I have some sort of probably more expensive leak in the rear. BUT IMAGINE MY, um, ANGST, while, in the midst of cleaning oil, I see a Febi ensignia on my tensioner!! And that's where I am. I cannot believe I've got a trunk full of MB parts and now I'm wondering if the whole job has been done with aftermarket parts which I tried SO HARD to avoid.

One question I have is whether that tensioner can simply be removed and the MB tensioner put on. Is it as simple as unbolting one and bolting on the other? If they swear the guides and chain are MB, and I could swap out the tensioner, that might get me to where I was hoping to be - but of course how can I trust whatever they say at this point.