Rusted Rear Diff
One of the drawbacks of living in Oregon is the ocean salt that gets in the air. I would also think the truck could of spent some time in the PDX area and the salt air their can cause the rust to start doing it's thing real fast. Heck the salt air can also get to the eastern part of the state where you live. FYI, I'm speaking from 15 years experience from living in the PDX area & 5 in Eugene.
if you think it will be an issue you can pull the cover off, take a wire wheel to it to remove the rust then paint it with some rust inhibiting paint and your good to go. or you can get a mag-hitec or PML cover and add about a quart more oil to the capacity.



