Starting a BB Duster project

I ordered a few thermostats from Summit so I'll see what they look like when they arrive. I never paid too much attention to thermostats before. Found out that Stant makes three different thermostats for big block Mopar engines. They have an econo one, an OEM one and a Premium one. I have no idea why a company like Stant would make three different thermostats for big block Mopar engines but they do.