another vote for 3.5
A couple of hints-
get some buthchers twine and tie the wings and legs as close to the body as possible. This will keep your legs and wings from turning to crunchy cinders.
Start out with Temp. of 380ish( using peanut oil) and lower bird SLOWLY into fryer. The temp should drop to around 350 and this is where you want to stay.
Leave temp probe in grease and check constantly. As the bird cooks your temp will start creeping up. By the time the bird is finished, my flame is almost off.
let the bird rest for at least 15 minutes after cooking, before you start carving. If you cut immediately, your juices boil out and the meat can end up dry. hth, Robert