This is my ride...2000 Nissan Xterra 3.3 V6 4wd: once in a while when it is quite cold out, my truck will make a grinding noise (sounds like its coming from the front left wheel) within the first 200 meters of me driving, which gets progressively louder. when i slow down it ends with the...

I don't understand why I can't find a simple needle bearing without having to buy a whole front knuckle assembly for almost $300! does anyone know where a suitable bearing might be found?(I've checked all the auto parts houses)