Nothing is cheap for a diesel; parts or labor (unless you do it yourself). Taken care of though there are guys on here now that have over 300k on their trucks and they still run like a top. JWC9 is right. Any number of things "could" go wrong. With 25 posts or by becoming a paid member of this forum, you can get the VIN checked and it will tell you what kind of warranty or GM specific repairs have been made. It is quite useful.