An adjustable portal box assembly for selectively mounting a wheel to an off road vehicle in either of two positions. The assembly includes a mounting plate mountable to the suspension of an off road vehicle, and a portal box is mountable to the mounting plate. The portal box includes an input shaft opening for an input shaft, and an output opening for an output shaft. The portal box is mountable to the mounting plate in a first position in which the output shaft is positioned to extend the wheelbase relative to the input shaft, or in a second position in which the output shaft is positioned in vertical alignment with the input shaft.