The only difference I can see is that on one set of tensioner arms (CE0312), there is a thread on one side where the axle passes through and the other side is not drilled. On the other set the hole passes through both sides of the arm and neither side is threaded.
Can anyone remember which is the correct style part and if there were any other differences/corrections made to the Early idler parts
<Later...>
Just found the article in the old Forum entitled "Tiger Idler Tension Arm" which seems relevant and advocates three possible solutions, one of which is to drill through the arm, so I'll use the drilled through arms and discard the others.
Still interested in why I have so many duplicated parts...
Adrian.