2002 Ford F250 squeaky front end?

I have a 2002 Ford F250 Ex cab short box with the 7.3 diesel, anyways the trucks front end likes to squeak only when the steering wheel is Straight and going from 5 mph to around 40 then i cant hear it anymore from the noise of the engine, that brakes and pads are brand new and i just greased all the fitting in the front end that seams to help for a minute then it started up again , but the squeak will go away if i apply the brakes just a little even. i have pulled the tires off and checked everything and it all looks at it should nothing broke or missing. it is a solid front axle and the truck has 196000 miles on it but ive seen these trucks over 300K and the front end dosnt do that , what could it be?