Why would you even get a solid axle truck to put 31s on? <img src="/forums/images/graemlins/confused.gif" alt="" />

If you want to lower the rear just take out the lift blocks, though this might require new shocks and/or u-bolts (as you noted). I don't think that you are going to be able to lower the front to match though, particularly if the truck has high crossover steering on it.

Harry Wagner
Harry Situations
4x4Wire's Toyota Section