the best un-restored example of a '68 Belvedere coupe just sold at auction, it was driven by the owner for a year before he died of cancer, his widow and son only drove it rarely after that until 1974 when it went to long term storage. 18k miles are all it ever covered

the usual things have been replaced, voltage regulator, water pump, gas tank, brake pads.

About a year after purchasing the car, Roland sadly died of cancer. The title was transferred to wife and son. It was driven very little after his passing but the journal mentions his son Joseph driving it to the hospital in Ann Arbor several times to visit his dad. From 1969-1974, it was stored every winter and pleasure driven only. From 1974 to July 24th, 2008, the car was kept in dry storage and the engine was turned over by hand.

In 2008 his wife passed away his son took the car out of the garage and into daylight with only 17,640 miles on the clock. Once Joseph got it home,  he worked to put it back on the road over the next few years by replacing the gas tank, rebuilding the carburetor, new brakes, re-coring the original radiator and installing a new water pump to make sure it would be reliable.

http://moparconnectionmagazine.com/one-for-the-books-unrestored-18000-mile-1968-plymouth-belvedere/