The later model " B" uses a larger sway bar than te earlier ones. It may be beneficial to try to switch to this if you have enough room. Part of the problem is the later b sits about 2" higher than the earlier ones. The later b is the rubber bumper ones. The 79-80 hae the larger bars. Also check your suspenison bushings in the rear axle and if worn consider using urethane bushings as a replacement as they are much stiffer. Other things to consider is putting gas shocks on the rear instead of the lever type that are currently there. And in other cases you can put a panhard bar on the axle or have it done to prevent the axle from moving under hard accelration. This would equire welding though and you could use do-it- yourself kit for this.