I have a line on a frme and axles for a 81 fj-40. I know the flangs are different, are these a better axle an frame? I need to up grade axles, for I have a 67 with 10 splines. Or should I look for around a 70-74 axles. The split case t-case of the 81, will any of the 67 gears fit? I would like to keep the lower gears.