Think about it, when you angle the transfer case down, you are lessening the angle on the rear shaft, but increasing the angle on the front. You cannot drop a mated transfer case straight down unless you lower the entire engine, transmission and transfer case assembly. To keep the U-joint angles correct, the transfer case and axles should all be left at the stock angles. The only way to really help the driveshaft angles is to use a double cardan joint on the rear as with the front shaft. With the D/C joint, you can angle the pinion up so that it is inline with the shaft and lessen the angle through the D/C joint. The front axle can be done the same way, but you will completely ruin the caster angle and end up with a truck that is undrivable. The fix for this is to cut the C's off the axle and rotate them and re-weld them so that the pinion angle is improved and the caster angle is preserved. Naturally this is not an easy thing to do and is not for the backyard mechanic. Even with the angles fixed you can run into pinion bearing lubrication issues due to a low fluid level or leaks when the fluid level is increased to keep them lubed. Which is why there are so many spacers, shims, drop kits and other redneck fixes out there that cause vibration and binding. They generally may help the situation a little but are just a band-aid and not a well thought out fix. The only way I know of to make a driveline work without major modification is to use drive shafts made to operate at large angles like those offered by High Angle Driveline and Woods but they are rather expensive. You can get some satisfactory results by running better quality joints and grinding the yokes for more clearance but this is another band-aid and not a real fix. The real problem is by lifting a truck, you take it outside it's design parameters so naturally there has to be a price to pay. Most tolerate the vibrating drivelines, low U-joint life or expense of custom driveshafts as the cost of driving a lifted vehicle but few take it to the level of redesigning the system to operate properly. As with everything there is a price to pay, one way or another.
