The kit requires the front gearbox portion (the first six inches of the case) of an NP203 transfer case. Luckily, these cases are readily available at just about any wrecking yard in the country. We paid $300 for this complete unit. It came out of a '70s-era Chevy 3/4-ton pickup. Off Road Design recommends getting a 203 from a '73-'77 pickup equipped with the Turbo 400 automatic transmission. This is preferred because it has the strongest input shaft available (32-spline) on NP203s.