Ha Ha no good on ya James, I will try and let you know what I know about them, the one with the short snorkle is a model 5 series 2 with a later model engine No, as far as I know the series 2 did not have any letters in the engine No and I think also the series 1 which is the one you have with the long snorkle, the series 2 does not have the axel extensions on the front and back which were left over from the model 4 run (for the flap to hinge in) the series 2 should have the long snorkle but I think some of the last run series 2 got the short one as the series 3 was being releast (no edger groove in the base) both have correct starters on them and the series 1 starter could have been a wire rope starter???. cant see to much else I can tell you from those pics, good luck with the Model 4.
