Hey man its probably your lower or upper ball joints, even if they are goin bad you wouldnt be able to tell in the steering, and theres really no way to grease/lubricate them. My lower ball joint on my passenger side squeaks a lil bit every once in a while ,but im not gonna change it til it gets really bad. But if yours is squeaking all the time that would drive me nuts and i would have to change them.

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2000 XLT 4x4 EXT. CAB 4.0/Auto Trans/3.73 gears/
31x10.50 BFG Rugged Terrains on MB Motoring Wheels/Pioneer Head Unit/JBL 12"/Camo Interior/'03 black and grey 60/40 seats/ green LED's Under Dash/T-Bar Crank/Windows-20% on the front, 5% on the back/Mustang Dome Light/06 Tails/