hit a rock
 

I was off roading and ran over a rock the size of a basketball, it first smacked into the front part of my front axle, other than rock dust all over it it seems fine and not dented at all, then it hit these metal bars going under my truck that look like support, they look dented up but i dont think they really got damaged to bad to where they need to get replaced since they are support. The part that really worries me is this long metal pipe that goes from the transmission to the rear axle got a bit of a dent at the very back of it near the rear axle. My buddy said that since it was only a dent in it and it wasnt acctually bent that it wouldnt matter. But when i was driving back on the highway it felt like it was vibrating more, other than that it seems to run the same. Im just wondering if anything will need to be replaced or if i should be fine for the most part.

Time for a new rear drive shaft. I wouldn't drive it too much until you get it replaced. Or you'll end up replacing your pinion bearing and seal too

What about the front axle that took the hardest hit? Was it strong enough to handle it? How about the metal bars that run from one side to the other? Since there dented will it affect the trucks support?

Crossmembers and skid plates are going to take lots of hits on 4x4s but its the drive shafts that aren't so forgiving.
Which ever drive shaft took the hardest hit and shows the most damage (dent) should be the one you should replace first to see if that alleviates the vibration.
To save cash I would order it from a auto recycler

If you jack up the whole truck or put it on a lift, you should be able to put it in gear and see if the shaft wobbles.......