F150 Rear Axle End Float

I have a '89 F150 2 wheel drive with the semi-floating axle differential. It appears to have excessive axle end float. Can someone advise me of the allowable specs and the likely cause of the problem? I believe the rear axles are retained by circlips accessed through the rear cover. Is this correct and is there any known problems / rectifications that you could advise me of.

Thank you

I have an 89 F-150 4x4, sitting at the studs push and pull play should be roughly 8-10 thousands of and inch. But i would check the diff yoke pin for any damage and go ahead and replace the c-clips, check your spider gears for abnormal wear as well, besure when pulling your rear end apart to mark everything where it is and put it back where it belongs.

Thank you for the advice Carrb 24