hey... im pretty sure it might just be a bad u-joint but i just wanted to ask before i change it out.. going from reverse to drive.. or drive to reverse.. pretty much whenver the drive shaft switches directions.. i hear a clunking noise in the back.. sounds like its cracking acouple times then stops.. i think it might just be a bad u-joint twisting over.. but i pushed up on the drive shaft and it isnt loose at all.. how else can i check it? or is it for sure the u-joint??