Nissan engines typically outlast the transmissions with proper maintenance. I've seen many pathfinders with 3.0 engines (same design as the 3.3 in an X) go 250k+ and still run very strong. Auto trannies are another story.....start looking for replacements any time past 100k, depending on usage. You can prolong their lives with regular fluid flushes.

67k isn't too many miles. Haggle on that price and drive it home for 11,500.