No you cannot. The outut shaft on a 4x4 is different then the output shaft on a two wheel drive. they have different spline counts and the 4x4 Tranny has a different extension housing to bolt the Transfer case to.
Most of them actually have front wheel drive, but more and more new ones are coming with all wheel drive (not necessarily quite the same thing as 4 wheel drive or 4X4). Some people also like to customize their vans and retrofit them with 4X4 chassis.
I found a listing for a 1988 Mazda B2600 ( 2.6 L 4 cylinder engine / 3 speed automatic transmission / 4X4 ) and listings for 1990 through 1993 Mazda B2600I ( 2.6 L 4 cylinder engine / 4 speed automatic transmission / 4X4 )