Ive got a 2005 GMC sierra with about 58,000 miles on it. when i got in to leave it was in 4wd and wouldnt go in 2wd until i started moving and when i stopped to take off it wouldnt pull until i put it back in 4wd. and now it wont go in 2wd at all. im gonna check a few things but i dont have much experience in the new 4wds. any help is appreciated