I recently come across an almost complete lower engine case on Craigslist for a Norton. It was listed as a Triumph. But after I went to look at it I just knew I had to have it for the sheer coolness of a pre unit single cylinder! I brought it home knowing it wasnt a Triumph engine. So I began searching the great WWW and was able to identify it as a Norton. Now I am reading and have become very confused as to what it is exactly. This is what I have gathered from one piece I have read. And PLEASE correct me if I am wrong (this is why I am posting this) that the Norton B3T was a Trials engine or prototype that later developed into the 500T. Now the fun part PARTS!! I have seen cylinders marked from sellers as AJS Matchless Norton. Are some or the Brit motorcycle engine parts interchangable? Can somebody please help? I cant figure out how to put a pic up on here!!!