i have a 98 ext cab 4x4, when at slow speed (around 5 or 10 mph) the front end has a griding noise. its almost like the t-case is engauged when i does this but it only does it about every 2nd or 3rd rotation of the tires. it dosnt make the noise in reverse. i took the hubs off and backed out the driveway and pulled back in and no noise???? i looked at the hubs but nothing seems to be broken or cracked. please help!!!