Re: shackle reversal
like jeepgod says, most of the kits (like MORE's) move the axle forward for you - MORE's moves it 1.5 inches forward. I moved mine 1 inch forward, wasn't enough with 35s and MASSIVE body trimming.
You need a longer driveshaft because you're moving the axle forward. You need a longer TRAVEL drive shaft because you'll need WAY WAY WAY more slip spline to keep the driveshaft and/or tcase together.
In STOCK configuration the spline doesn't slip or move that much because the shackle on front tends to move the tire BACK as it droops (when the axle's natural tendency is to increase the distance between the axle and tcase), and AWAY as it compresses (when the axle's natural tendency is to decrease the distance between the axle and tcase). This causes the spline to not move that much because the shackle is actually working to conteract the natural tendency of the axle to move away from or closer to the tcase.
However, with a SRS, the shackle (in back) tends to more the tire AWAY as it droops, and closer to the body as it stuffs. In other words, in SRS front suspension the shackle is working to INCREASE the natural tendency of the tire to move away from or closer to the body of the rig. The result is that the spline on a SRS rig has to be WAY longer in order to not pull apart or get stuffed into the tcase - I was amazed at the difference in travel required. If you cross it up much at all you WILL have to buy a custom long travel drive shaft or it will either stuff itself into the tcase or pull apart.
Just imagine the shackle as a pendulum that sways back and forth in response to suspension movement - it has to in order that your springs are able to compress and extend. Now imagine what that does to where the axle placement is.
I had the shaft pull apart on me once, then ordered a custom unit. The natural tendency is to use the stock shaft, maybe have it shortened or lengthened as necessary, but this won't be enough - it will either pull apart on extension or jam into the tcase on compression. Did you see top truck challenge? See all the driveshafts pull apart? see the transfer case adapter get broken? All because there wasn't enough travel in the slip splines in those d shafts.
Chad - Been there, done that!
Chad Lloyd 95 YJ 4.0 NP435 EBD20 woodies D44s 4.88 detroits SOA revolvers 35 X 15.5 SXs 8274