Wally, I was assuming that you want to heat the oil; possibly in addition to the coolant. I have used a tank heater with good results on my 302. But they don't heat the oil.
The oil heater is Jegs p/n 861-6770. You drill a hole in your pan, weld a bung on, and screw the heater in. It has a stainless sleeve to prevent direct contact with the element. I have not used this heater but I like the concept.
