We have a 2003 Gulf Stream Yellowstone Country Club. We purchased it three years ago and it had a 40K. Over the coach is very solidly built. The best advise I have is the same as most of the other responders. Have it checked by a diesel technician and ask for maintenance records. Unfortunately we didn't have a tech look at it and the owner did his own maintenance. 6 weeks later we were the proud owner of a remanufactured Cat 330HP engine. Maintenance records are the biggest item for used RVs. All the Gulf Stream owners we have seen since we purchased ours all have had very little problems with them. All say they would buy them again.