Tech article by Jon Hanna (Admin)

Following are photos of the popular NP435 4 speed installation. This transmission is a much stronger unit than the original 3 speed found in most early Broncos. 2nd, 3rd and 4th gears are comparable to 1st, 2nd and 3rd gears in the stock 3 speed. However the NP435 has a much lower 1st gear (sometimes called a "granny" or "creeper" gear) which allows for much more control when rock crawling.
Comparisons of the stock Bronco 3 speed and NP435 4 speed.
Installation from below.
Shifter hole and cover plate.