8.8 swap

Just did this swap, and i noticed something when shaking the car. I have a slight tapping in the passenger axle. I know the c clips and the axles cause them to have a tiny bit of play, but does anyone know the exact tolerance or play that i shoul have? Or should i have absolutely no play?

Btw.. the stock length explorer rear end fit in my 72 dart, but that was with stock 98' mustang wheels. The backspacing on those should be around 6" though. Im not exactly sure off the top of my head. I chose to cut it down so i could use my torque thrust wheels though. i did the slug inside the tube and drilled through the axle tubing.