8.25 Questions?

I am changing the brakes on my 1998 XJ, it has a 29 spline 8.25 in the rear. The axle has about maybe 1/16" of play in it, if you pull and push on it. Is this ok? Also changing the rear diff fluid and noticed that the inside of the carrier is very dark, the stuff rubs right off. What could that be from? Also is a no-slip a good idea for my XJ. Hear alot of yes and no.
THANKS

Yes, it's normal for a c-clip axle.

And yes on the No-slip.

Yup thats pretty normal. The dark stuff is probably just gear oil. There's always going to be very very small shavings in the oil, just enough to darken the color, that's why you change it. The 1/16" play is fine. Thats just the c clip tolerences being a little lax. We are going to need to know what kind of wheeling you are intending to do for a locker choice. If its mild wheeling, mostly mud, etc, the no slip will be fine. I run a detroit in mine and it is very quiet and has great street manners. I also don't think it will ever be failing on me. I've heard of multiple no-slips failing in the 8.25. If you are regearing, save up and go for the detroit. Easy as that.