i high pinion axle has to be created as a high pinion axle. you cant convert a low pinion to a high pinion, unless you have something that has a removable 3rd member like a ford 9"
you'll need to scavenge for a used high pinions for up front out of older trucks and convert them or get one from SOLID, Dyna Trac or Currie.
the difference between a low pinion and the high pinion is purely at the differential. the pinion is obviously at the top of the diff instead of the bottom. the only change inside is the fact that it uses Reverse Cut gears.
thats pretty much it.