Call all gear heads!!! I've got a problem with my "new" old truck. The truck is an '87 F150 with 89,000 miles on it. When i put the truck in gear (automatic ), I hear a "clank". At first I was told that it was prolly the U-joints. I checked them, no movement what so ever. I got back under the truck just now and I was able to twist the drive shaft and 1" or so in both directions and I was able to make the "clank" sound. It was coming from the differential. My FIL said, it may be cheaper to by a salvaged complete rear axle. I'm not sure my skills are up to the task of disassembling the differential and fixing it, I know there are many moving parts in there but is it that difficult? Thanks in advance!!