You are going to need the hub seal tool. Depending on year you'll need this. That hub seal you need, and your 4x4 wont work right if its not on there. Needs to be airtight fit.

2005+

https://www.amazon.com/OTC-6698-Knuckle-Installer-Current/dp/B004FZCH70/ref=sr_1_2?keywords=6.0+hub+seal+installer&qid=1570149049&sr=8-2

99-2004

https://www.amazon.com/OTC-6695-Shaft-Installer-1998-2004/dp/B0015PKC5W/ref=sr_1_1?keywords=6.0+hub+seal+installer&qid=1570149049&sr=8-1