A certain amount of what you are describing is normal. There's lots of splines and gearsets involved, a little play here and a little play there all adds up.
Have you verified that the wheel center tapered hubs are TIGHT and haven't been moving around, wearing the key that engages with the slot in the axle shaft?
If the transmission and final drive seems concerning, the first thing I'd do is check for filings in the filters, and drain the oil and remove and check the transmission pump suction screen for metal.
Insert a shop magnet in the hole the screen was withdrawn from and see what you can pick up in the very bottom of the sump.
You're gonna find at least SOME "silver glitter".