how long are the ladder bars? I had a similar problem when I built my s-10. I made my ladder bars too short, so it would hook good until just before the 60' mark then the bars would actually beging to lift the rear of the truck instead of pulling the weight back onto them. from looking at yours, the upper link mount looks awefully close to the centerline of the axle, I would think it should be up a little higher. also what is the pinion angle at? should beabout 1-2* down at rest to allow for some reaction and slack in the suspension components. u joints are the strongest when they are straight. I would check over the suspension geometries some before swapping springs around. unless you happen to have a few just lying around, or you know someone who does so you can try some different rates and see what works best for you. also, on alot of drag only applications, they will use a slightly stiffer spring on the right rear than on the left due to the fact that once you rear end reacts, there is a twisting force down on the right rear, and a lifting force on the left rear. they offset this with the stiffer spring. thats why on a lot of cars that pull the front end, you see them twist to the left. just some things that may help you. good luck, glad to still see some people going fast the traditional way
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