I'm curious for answer, my front ds has been bare metal splines for 6 months or so, hasn't failed me but there is definitely some extra play between the halves
The joint was binding up with the blue stuff coming off. I removed all the blue stuff and then the slip joint was too loose. I feel like it will cause vibes on a street driven vehicle. For those buying used driveshafts this is one of the things that you must check before purchasing.
The blue glide coat is very necessary on a street driven vehicle. It takes up a few thous. on slip to insure the slip and stub have proper engagement. Without it the tolerances are to loose and will cause a vibration. Grease only lasts so long and is not a long tern solution.