I am starting to restore a old Norton I have had for 37years, and have a question about the frame number. This is what I have vertical line of numbers 53319 I am assuming serial number, then horizontal line starts J1 and it is getting hard to read the rest of the model number, Is there any way to tell from just the serial number??? The right upper frame tube has a indent that looks like it is for the bevel drive of a long stoke motor. is the Manx the only bike to have this indent? the upper rear transmission mount is not welded to the frame( normal for a 54). Being a J make it a 1954 and the serial number agree with that, It seems it could be a J11M2 M40 Manx or a J122 dominator 88 (why would a dominator need the indent?). I just do not want to start and find out later that it was a Manx, I might take a different direction rather than build it back as a Triton/Weslake