Miatav8,MstrASE,A&P,F wrote:
I'd check the spiders, side gears, clutches, and steels. If there is no obvious damage inside, looseness, or noise, I'd let it go.
I agree. Most of the aged Ford diffs I work on have a lot more play than that! The diff in my '94 F150 has worn the the center pin/carrier to the point that I'm worried the pin retaining bolt will snap off. I'll cut it some slack, since the truck just turned over 209,000 miles.
If the clutches/steels are good, it's possible there is some spline wear on one side gear/axle. You did put the wave spring in, right?