We just purchased a 2005, 3400RL, and I also own a '02 Chevy 2500HD, crew cab, Duramax diesel.... I do not have a "dullie"... but I have found that with the proper tires and a sliding 5th. wheel installed... you really do not need a "dullie" unless you just want to spend more money or want the extra safety of the two tire set up.... I am a truck driver and I believe the single tire is fine when properly set up..... ask me any questions and I will respond... I love the camper.. we have not taken it out for the "shakedown" cruise but are planning it in November..... good luck and write me anytime...............
