I can't agree that you need a IFS to drive on the highway. I have 40 K on my 50 with a straight axle and have a 100 mile round trip commute. I have changed the tranny to a t-5, sway bar, gas shocks, radial tires and kevlar composite brake shoes. I drive 70 to 75. I try to keep the limitations of the truck in mind and avoid 75 in the left lane one car lenght away, like most people drive here in CT. There is no getting around the high center of gravity and narow axle width of these trucks but I'm not about to lower mine or put in a car suspension. Thats my personal preference, I want to still feel like I'm driving an old truck. Discs are better but the Kevlar shoes I use aren't bad, I notice no fade. I keep in mind I may not be able to stop like a four wheel anti-lock disc setup. Here if you leave 10 feet of room to the car in front someone will squeeze in a 9 foot car and then hit the brakes. I often try to find a light trailer truck and follow behind, seldom will anyone pull in front. I also look for two lane state highways when I can.
When I couldn't decide if I wanted to rod my truck I put in a Borg Warner OD and drove the 216 for a while to get a feel for it.
