I have one in my front shaft as well. Although I put it on my t-case side as thats where i was having the binding issues... Like others mentioned, vibrations at about 20ish and seem to mellow out around 30... but I RARELY ever go that fast in 4WD since I RARELY drive the Great Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley thing...
Been holding up so far!! Probably should grease it before winter actually...
78 Cherokee N/T with 10B/D60, SOA, TT's shackle reversal, 35" Toyo's, 360 with a Holley on top, t15/d20 and a lot less $$$!!