You either need to find an early 80's Jeep Wagoneer Dana 44 or have a custom housing made with a left side drop and use factory Toyota parts to fill it. The custom housing route will be the most expensive but probably easier to get the parts than finding a Wagoneer front axle. Also, the I believe the Wagoneer axle will be the same width as your 4Runner's rear axle. If you have the Toyota axle made to stock width you will need 3" wheel spacers to match the rear. If you have the custom Toyota housing made to match the rears width you will have to have custom axle shafts made too.
