Oni-Cam

I need some help. I think i screwed up my u joint on my driveshaft. I dont know but, whenever i start to move, the car makes a kind of pop sound, and i thought it was an axle, so i took both wheels off, and both axles are fine. then i started thinking, and i think i might have screwed up my u joint. If anyone can help me out, and maybe tell me a roundabout price of how much it would cost to fix at a transmission shop that would help a bunch.

oni-Cam