offroadz

Ok here I go, ive been having a noise in my truck since the end of last winter but I just got it back after being in an accident. Now i need to fix it, when I am driving it makes like a roaring noise, as you start to slow down it changes its pitch but when you speed up its like a constent noise that you can hear in the cab, I was told it was the rear end so me and my brother opened the rear end to find out everything was fine(check the pinon for play). I dont know much about mechanics so im lost and I dont want to take it to a garage to get the run around. Any ideas to helping solve this issues would be greatly appritiated.