Thanks to you all, and another friend I am very pleased with my first Prime in the FEC100.
In years past I had worked out of convection oven at 350 degrees. I heeded the advise about carry over and pulled at 120.
I have the old Traeger controller.
Seared the rib all over and put it on the smoke setting for an hour. Bumped it to 250 for two hours and dropped it down to 200 for the remainder. When it hit 220 degrees I wrapped it in plastic wrap and foil and dropped it in the cooler (cambro) until service two hours later.
My guests and I were very pleased with the end result.
Prime Rib
Plated Prime Rib