Most Helpful Guy
Yeah, I'd check into getting your tires balanced. If it seems to shake when you're going a certain speed then your tires are "wobbling" while they spin and that causes it to shake when they get spinning that fast. It may very well be something to do with your suspension as well, either causing the body to shake or throwing off your center of gravity (or something fancy like that). So now that the girls aren't paying attention to this answer anymore, if you search on Google the internet is chalked full of free p*rn sites. If you do a search for amateur p*rn, you'll find plenty of free sites to fill your needs.
So yeah, good luck with your truck ;)