They seem to be ok. I don't see slack, but when I decelerate from (say) 80 mph to 72 mph, I get a faint vibration. No vibration on acceleration. This may be due to a worn drive plate, so I can't indict the Cardone driveshafts without more research. I can't complain, broadly speaking, and the boots are fine, so they have lasted a while (and boots are often lame on non-OEM parts).
