The Countach was available in a total of 7 different variations in its lifetime. Some of them were not truly "available," as they were prototypes. The variations include the Prototype LP500, the Production LP400, LP400S, LP500S, 5000QV, 25th Anniversary, and Walter Wolf Countach.
There were 3 different variants of the V12 engine used in these cars. They were the 4.0 liter, 5.0 liter, and 5.2 liter. All of them were mounted in the rear, as is custom in the supercar class of cars.
This car was a trendsetter in styling, making it a popular choice for both celebrities and the movies they starred in. The Countach had cameos in such films as The Cannonball Run I and II, Rumble in the Bronx, and Rain Man. It's also in muliple video games, including a copycat called the Infernus in Grand Theft Auto: Vice City.
2,042 Countaches were built at the Lamborghini factory, making it one of the more common cars from the brand to date. They are still in high demand, often commanding six figures. If you are interested in buying one, you can get the best deals at collector car auctions and on eBay, where I guarantee there are at least a couple Countaches listed right now. There are also often parts, both original and aftermarket, on the popular auction site.