I put a 90 style swing arm on my 86 and the bushings from the 90 arm go over the 86 bushings so you can still use the 86 axle however you have to shorten the bushings and locktite them, or you have to drill the frame to take the larger pivot bolt also dont over torque the bolt use the minimum torque value not the maximum or else you will bend the frame and put a lot of drag on the swingarm, also you need to make custom dogbones and a spacer to replace the eccentric in the linkage of the 86 that has a hole in the midlle so that it is no longer an eccentric.