Original Electro 35 1966, GT introduced in 1969 and produced until the GTN in 1973.
I previously wrote about the GTN. The big difference I have seen is that the top shutter speed on the GT is 500 and the top speed on the GTN jumps to 1000. They look and operate basically the same. Both the GT and the GTN are black finish. The Electro 35 came in a GS and GSN as chrome counter parts to the GT and GTN.
This is a great (full size) fixed lens rangefinder. They are getting on in age and have some known electrical risks. (see the Yashica Guy link below for some tip to DIY service). The lens is a fantastic clear f1.7 that make this a nice low light shooter. The one weakness I see (other than age) is that the viewfinder is not as bright as some of the other fixed lens rangefinders. Not so much of an issue in normal use but does impact the use in low light: too bad given the fast lens.
If you have not shot the Yashica 35, you should. It is a great shooter that will give you a warm nostalgic feeling and some nice images.
Lens: 45mm Color-Yashinon DX f1.7
Film: FujiColor 100