P11A and P11A Ranger were numbers in the range 124372 to 126123 and were built in three batches. As far as I know there is no distinct division where the P11A became the P11A Ranger. There were constant improvements to things like the oil tank (5 variations) and the change from aluminum fenders to chromed steel. The US importer did not help matters as he issued a letter to dealers that all P11A's on the floor would be called P11A Rangers.
The early hi-pipe ('67; 4 batches) and the last series (Ranger 750; 1 batch) are more clearly defined.