I've dug around a bit and this is what I've found -
1965 - 500F announced as a replacement for the 500D. Major changes were the front hinged doors and slightly more powerful 110F series 500cc engine. For Colm, the rear badge said 'nuova 500'
1968 - 500L announced. Detail alterations only. Engine the same 110F unit and chassis numbers continue with 110F prefix. Rear badge changed to '500L' with a similar change to the 500F badge.
From 1968 until 1972 both 500F and 500L were in production. I guess you'd call these cars the Series 2 500F and the 500L, though the distinction in the case of the 500F seems more academic than real.
1972 saw the last of the Bambinos - the 500R. The floorpan was from the 126 series though confusingly the last of the 500Ls also shared this floorpan. The engine was the 126 A5 600cc unit.
So which is a Series 1 500F? I guess the answer would be a car manufactured between 1965 and 1968. My 500F dates from around 1968 with a VIN that seems to agree. It must be a transitional Series 1A car
Also, my door hinges are the 8 bolt variety - if anyone has another style please post a photo of it as I'd like to see the differences. The hinge rebuild kits are the same for all front hinged cars - F, L or R.
Hope this hasn't confused you guys too much - if so, suck it up cause there is no simpler way of explaining it
Chris