The first Grand Am was based on the GM A platform. It was designed to compete with the luxury sports sedans coming out of Europe during that same mid-1970's period. The engine on the Grand Am was a 400 V8 with 2 or 4 barrel carbs or a much more powerful 455 V8 with four barrel carburetors. The 400 was available with a Turbo Hydra-matic transmission or a 4 speed manual.
The Grand Am name was retired in 1975, but it was brought back in 1978 as another A body based on the Pontiac Grand Prix. This car was loaded with power features including windows and locks, and it also had a sunroof. The sales numbers were not great, and the Grand Am was replaced by the Pontiac 6000 after the 1980 model year.
The Grand Am name was brought back once again in 1985, and this time it would last for a much longer time, not being retired again until 2006. The third generation Grand Am had a I4 engine standard and an option for a V6 engine. These were much smaller cars than the previous Grand Am models, so performance was not much worse in comparison. There was a turbocharged option on one of the I4 engines.
There was a redesign in 1992. The Grand Am would now be based on the N platform. Engine options were similar to the previous generation models.
The final incarnation of the Grand Am was introduced in 1999. It was sold in a variety of trims, including SE, SE1, SE2, GT, and GT1. The Grand Am would be retired in 2005 in spite of the fact that it was Pontiac's top selling car. The G6, which replaced the Grand Am, has had much more success and continues to be Pontiac's top car.
There are plenty of Grand Ams on the used car market, especially if you are looking for one of the newer models. Remember to figure out current prices by using final sale prices on eBay, and base any offers on that. You could also just buy the car from an eBay auction; once you get used to the system it's really a piece of cake and could save you a lot of money on used car purchases. You can also find parts on there.