I have a 1972 220D (Engine No 615912-10-239249) that I am about to drop a new chain, tensioner, guide rails and spockets into.

At the moment it has the Type A tension rail, has this been superceded by the Type B tension rail?
If not, can I use the Type B?

Any help greatly appreciated.

Merry Christmas to all.

I'm wondering if you mean by Type B Tensioner, the ratcheting type? I just replaced my tensioner and rails on my 69 220d & used the original Type A. There is nothing wrong with the design of the original so I think it is safe to stick with it. Someone more knowledgeable than me might know better though.

Thanks for your reply, Ralph.

I'am afraid I did not phrase my query very well.

My question is about the tensioner rail that sits against the tensioner.

Mine is currently the Type A that has the top of the rail turned down that sits against the tensioner.

All the sales sites that I have looked at only picture the Type B, which has a full length metal sleeve with a built-out bracket with a pin that sits against the tensioner.

I have now found that in the Mercedes service manual it states that Type B rails can be used inplace of Type A rails.
Then goes on to state that this does not apply to cylinder heads with "Chain Tensioner Oil Pockets".
How do you know if your head has "Chain Tensioner Oil Pockets"?

I'am now off to do more reseach

The old tension rails were steel backed and a rubber coating which the chain slid against (Type A). That is the type which was in mine and literally broke. I replaced it with the newer Type B, which is aluminum and has a rubber or nylon (I forget which) style face. Both types fit my car and I was also confused as to how you tell if your head or block has an oil pocket. I guessed that mine didn't (615.912) (1969 model year), just because I couldn't see anything resembling an "oil pocket". You need to remove radiator to extract the "thrust pin" which is the swivel point for the rail. If I had it to do over I might go with the old steel and rubber type (the old type). I just couldn't figure out then or now why the original broke, other than 36 years of age. So, if you have a 615.912 engine, both will fit. I'd suggest using a new thrust pin (a buck or so) with your new rail. I didn't have a slide hammer so used washers and a stainless steel bolt to pull the old thrust pin out. If I had it to do over I'd buy a slide hammer (my thrust pin was all chewed up, that's why it was hard to extract). I don't know if the thrust pin or the tension rail failed first. In the FSM, I believe, all of the alternate guide rails interchange. The only exception is the "oil pocket' deal. Like I say, mine's a 69 220d 615.912 engine. Merry Christmas,