I noticed this past winter that after I put my truck back into 2wd, it took a few minutes to disengage while I was driving down the road. sometime when it did kick out, it kinda clunked. anyways, yesterday I got into a little mud and had to put it into 4. I forgot and left it in four and went down the pavement. the truck was vibrating fairly bad. I took it out of four a few miles down the road. and when I got to my destination I noticed a grease smell and there was oil or grease around the inside of my fender well and around the shock and suspension. could not tell exactly where it was coming from. anyone have any ideas of what it might be before I have to take it to a mechanic?