Find the VIN# range for the 03's with the oil pump issue, and avoid unless there's PROOF it was already properly fixed.
Some don't have a CDL that will lock....I thought it was 02's but my late production 01 doesn't have the CLD lock nipple on it. Crawl under there and check if that's a concern.
Depending on what part of the country its from....check the frame rails and make sure they're not starting to rot at the welds. I think this is normally in the back that this can be a problem. Cali shouldn't be an issue but worth checking.