Make sure you get a sleeve type and not a poppet style thermostat. A poppet style costs cost five bucks or less, a sleeve type costs 8 to 10 bucks. Sleeve type can outflow a poppet style and will give a uniform / even temperature in the motor. Poppet style is always wide open then closed tight, you can watch it on your temp gauge - always up and down. I think in Summit or Jegs they call the Sleeve type a high performance thermostat. I know Robertshaw makes both types.