The Shelby GT350 has become one of those iconic cars that has defined an era. They are perhaps most recognized as having those famed racing stripes, even though in the first year only about 35% were made with those stripes at the factory, most restored models put the stripe on there anyway.
The 1966 Shelby GT350 was the first to be sold with an available automatic transmission. The Le Mans stripes were still just an option at this point, and no stripes were still the standard. The engine block was now painted blue instead of the black that was used for 1965. It should be noted that the first 252 of the 1966 model were actually 1965 Shelby GT350's being sold as 1966's. The parts and engine color were all the same as the 1965 model. About 1,300 of these cars were sold to the public in 1966, with another 1,000 being sold to the Hertz Rental Car Corporation as part of their "Rent a Racer" program. These models were dubbed the GT350H. Almost all were fastbacks, but there were 4 convertibles made that year. These are obviously considered to be among the rarest cars of all time, the holy grail of car collecting.
The 1967 Shelby GT350 featured the taillights from a Mercury Cougar. They also had a factory rollbar (the first in the United States) and side air scoops. This would also be the first year of the Shelby GT500, another modified Mustang with an even bigger engine. The GT350 from this year is actually about twice as rare as the GT500, and it could probably beat it in a road race as well. While the GT350 was carefully engineered for weight balance and tuned for the race track, the GT500 was just a Mustang with a very large engine dumped in it.
The 1968 Shelby GT350 featured the Ford 302 engine. The car seemed to be neglected by Shelby, as the GT500 was getting more sales and therefore more attention, including a number of limited edition models. The 1969 and 1970 models were identical, as Shelby had terminated his agreement to Ford in the summer of 1969. They would be the final years of the GT350.
I'm told that a GT350 is blown up in the movie "American Gangster" starring Denzel Washington. I'm not sure if I want to see that movie now that I know that.
There are several places you can buy a Shelby GT350. The obvious place is Hemmings, who produces a catalog along with a website that has classifieds. The other choice that I would recommend is eBay. There are usually several listings for these cars at any given time on eBay. There are also lots of parts and memorabilia.