Congratulations! I love it!it's premature to break out the champagne flutes, but I did have my LJ up to 71 after installing the UCF Extra clearance (1/4" steel) skid without discernible vibration. Being that it was coming in around 67 beforehand, I'm optimistic. I need to spend some time on a real highway to know for sure.
Since I changed my rear driveshaft angle by about 4 degrees (set the pinion back to half deg below driveshaft), and changed the front driveshaft by about 3 degrees without changing the pinion angle (now about 3 degrees below driveshaft), I can't for certain say it's the weight or stiffness of the skid vs just blindly stumbling my way into the right combination of angles...but if the vibes are gone at least up to 75, I'll take it. If they're gone up to 80, I'll buy lunch for the first forum member that's had this issue that finds themselves in the same metropolitan statistical area with me.
That skid plate has been on my wish list. However, after enjoying a couple of days of highway driving with my front driveshaft out (which makes the vibes go away), I gave in and ordered locking hubs.
Wish me luck with that upgrade!