HELP! excessive front end noise and vibrations

[Reiner29]

Could someone give me advise on this subject as well. Started to take mine apart so I could see if I needed a new hub as well as bearings(left front has noise that is speed dependant, yet can be heard when the wheel is spun by hand with rotor off) , but was stopped cold when I got to the outer lock nut under the manual freewheeling hub. This brass nut has slots cut into it, and I have not been able to find the required tool to get it off so I can remove the hub.

I have a 98 4X4 taco with a 2.7 motor, short bed. Thanks for any help you can give on this subject.