the early 6.0's were 50/50 on being good, if its at 91k and oasis is clear then you shouldn't have any issues other than the normal stuff. if your set on a 6.0 get the '06 or '07 models as they had most of the bugs worked out by then, they still have lemons though as does GM and Dodge. Friend of mine has a '04 F350 with 375k on it and only problem he had with the truck was a bearing wore out on his front hub. GL on whatever you buy!