I think that Mr Ribbett(sp?) (on this forum), search the classifieds, had a set of 5:38 torque tube gears. In my research for the later gear sets (u joint style) there is a listing for 4:86 gear but always with the notation Marmon-H(armon? name is escaping me this second) and discontinued, and 4:30 (also discontinued) for p-30 step vans till 1982 when the H110 went metric. I wanted a set of 4:86's for my truck, but settled for the last 2 sets of 5:38s in the country at $850.00 shipped EACH. My truck would not have looked right with any other axles in it so I bit the bullet, shed blood out of my eyes and paid the price.
My suggestion is:
Examine the HP your engine produces divided by the weight of the truck and the stopping power of the brakes. If the sum total of the above equals the truck being safe to travel above 45-52 mph (no this isn't a matmatical formula just something you must think about) then the most economical way to do it is to swap in a newer axle.
