The CV driveshaft I have was measured for when I was at 4.5" of lift, now that I'm at 5.5" of lift I see that 1/4"-3/8" of the splines on the shaft are visible. Danger zone or not a problem yet? With jackstands on the frame rail and shocks disconnect the axle can't drop low enough to pop the splined area out or even close to it. So I'm just wondering what is considered "safe".

I ran my 4" CV driveshaft with a 6" lift for over a year without problems. You just need to figure how much the splines will still be running together.