2005 quad cab 4x4, stock, both front wheel ujoints seized (each had one cap dry) around 45k, rear driveshaft ujoint squeaky (one cap dry) at 47K, Smarty downloader at 50K, Toyo 285/75R17 tires at 58K, ball joints and front wheel ujoints again at 67K, replaced clunking sway bar links and adjusted loose steering box at 75K.
Front wheel ujoints or ball joints are a bitch since the unit bearings typically get rusted stuck in the steering knuckle and they have to come out to do either job. I installed freewheeling hubs during the first ujoint change. BTW If you go with greasable ujoints you have to grease them often.
16.11 mpg overall average for 75K.
Typical mpg not towing is about 18 highway, 16 city and 12-14 towing.
Gauges are a good idea even for a stock truck and especially so if you are going to tow heavy or use power adders. If excessive smoke out the tailpipe during acceleration will bother you then be careful about choosing a power adder. Some are better then others and everybody has a different level of smoke tolerance. I use a Smarty downloader, it has worked well but do I wish it had a program that had stock like smoke levels or could be switched back to stock on the fly. Also remember that using a power adder may void what is left of the factory warranty.
Cummins forum is good, as is the TDR (turbo diesel register). Just remember that the problems will appear somewhat overblown on the forums because, lets face it, who is going to post that their truck is running fine?