The Bushmaster, lachesis muta muta is the largest Pit Viper in the world.
The Pit Bull is not a species, but a breed. So I guess the answer would be one.
Dodge Vipers were made from 1992-2009. They are out of production now.The average production numbers were about 1500 per year.courtesy of www.TheViperStore.com
The pits on a pit viper are between the nostril and the eye on each side of the head.
There is an article in Wikipedia (see related link) that shows the distribution of each sub-species.