I have a 98 frontier that i have lifted by turning up the torsion bars to the max in the front and i have put 2" blocks in the rear. the driveshaft is a two peice driveshaft with a hanger bearing where the two driveshafts meet. I have already had to replace the hanger bearing twice in the last 10,000, which is not expensive, just annoying, how could i fix this ****, so i dont have to take my driveshaft off every 5,000 miles?

 

You might try finding or having made a spacer block for under the center carrier bearing matching the lift of the rear end, (IE:2" block for 2" lift) if this doesn't work try one half the lift amoumt. You should be able to find a happy medium that the u-joints and the bearing can live with.
One other option would be to measure the total length of the front and rear shaft including the bearing, measure the rear shft, find the percentage of the total and have a block made equal to that same percentage of the lift. Don't skimp on either options. Use a quality hardened material and the proper hardness of bolts as you must remember that all the torque of your truck hinges on it!
Having worked on vehicles for a number of years this would seem logical but as always, NO GARANTEES!