Hi Vicman
This is all very interesting. Yes the part # are all the same as are the part# for the piston cylinder assemblies. On my older engines the box's , which I still have, say ABC but the instructions for each engine which I still have say the material used is ABN!!! So I think going back to at least 2005 these engines have been using ABN cylinders not ABC as stated on the box. This is like OS was doing, calling them ABC when they were really ABN. I would never even have looked at this except for Fizz bring it up

Denis