from what ive read supposedly the idi 5 speed trucks were supposed to have the 4.63s.the psd trucks were another that was supposed to have those gears.i have not found 1 450 with those gears.i have a 95 450 now with a psd and 5 speed that has 5.13s.
only thing you can do is deal with it.if you want a truck that gets good fuel milage and good highways speeds than an f450 is not the truck for you.these trucks were built to be workhorses and nothing else.they werent built to drive around in like a car like an f250/350 is built for.
owning an f450 puts you in the same class as a tractor trailer.you must have the doors lettered with a business name,must have DOT numbers,must have a DOT medical card,must have a DOT annual inspection(wich can take up to 3 hours in my state)its a commercial vehicle so you also need an IFTA (where applicable)sticker if you go out of state with it,any fluid leaks can and will cause the truck to be shut down and towed,then you cant drive it anywhere till the leaks are fixed and dot comes to your house or place of business to reinspect it.
for most people a 450 is not needed,as well as the additional headaches that go along with owning a commercial vehicle.an f350 thats setup right will do the same amount of work and haul the same loads as a 450 but without the extra hassles.