[AZKen]

Received my truck with loose parts, including drive shafts. Competed the Ujoints. All the while noticing a blue coating on the slip end of front drive shaft (4WD). I thought at first it was a cool slip surface put on for performance. I now think it's a protective coating put on after some sort of work was done on spline or other. Should I meld this off? It really is on tight like it was dipped. Tried to cut/scrape. What is it and what do I do. The yoke "goes on" but really tight, like pound on tight. Thanks. Pic enclosed. What bothers me about if it's temporary protective or to be used is that the splines have been slid into something when coating was wet because they are perfect and you can see the blue on the shaft is wiped by mating spline? Is this a way of rejuvenating a worn spline? The front drive shaft would seem to be the last place to be worn?