From 68 to 71 : beetles came as 1300 and 1500 models with amber top + red lights, only the 1300L and 1500L (L=Luxe) had the reverse light.
From 71 (1302) to 73 (1303) : they all came with reverse light.
Probably reverse lights were option as you stated in your later post.
For example, my friends '72 1300 model came like this:
On the other hand, my '70 1300 model had reverse lights from the factory: