The main difference between a front and rear third member is the placement of the ring and pinion gears. In a rear third member, the ring gear is located on the bottom, while the pinion gear is located on the top. In a front third member, the ring gear is located on the top, while the pinion gear is located on the bottom. This difference is necessary to accommodate the different directions in which the driveshaft rotates.
Another difference between a front and rear third member is the offset of the pinion gear. In a rear third member, the pinion gear is offset to one side to accommodate the driveshaft. In a front third member, the pinion gear is centered to allow for equal clearance on both sides of the axle housing.
To use a Toyota rear third member in the front solid axle, you will need to make the following modifications:
Change the position of the ring and pinion gears. This can be done by rotating the third member 180 degrees.
Reposition the pinion gear offset. This can be done by using a different pinion gear bearing carrier, or by modifying the existing one.
Ensure that the third member will fit correctly in the axle housing. This may require some minor modifications to the axle housing.
After making these modifications, you should be able to successfully use a Toyota rear third member in the front solid axle.
