1995 Dodge 1500 rear end problems

My 16 year old son traded his jeep for a 1995 Dodge Truck (http://www.2carpros.com/forum/here-vp808810.html#) 1500, drove about six miles and something popped and it started making an awful noise. He had the rear end checked and there was damage to the gears. He was sold another rear end from a 2001 Dodge truck and drove about 20 to 30 miles. He put the truck in reverse and it made a very loud popping noise and tore up again. At first the truck wouldn't go into gear and had to be scotched. Later it started going into gear but the rear end was destroyed. What could be causing this to happen? Could there be something going on with the transmission[ (http://www.2carpros.com/forum/here-vp808810.html#)? The truck has also been raised up by the previous owner. Could that have somthing to do with the problem?

Did they change out the complete housing or just the ring gear and pinion?

They changed out the complete housing. Someone replied one problem was the fact it was being driven by a 16 year old boy--he had just traded for the truck when it broke down. Didn't even get ten miles in it...