SpaceX To Test BFR Technology On Modified Falcon 9 Upper Stage Written 8 November 2018

Space News reports that SpaceX CEO Elon Musk outlined plans Wednesday to “attempt an orbital flight of a reusable version of a Falcon 9 upper stage by the middle of next year to test technologies for the company’s next-generation launch vehicle.” Musk announced the modification in a series of tweets in an “apparent reference to a path of upgrades the company is pursuing as it develops its Big Falcon Rocket (BFR), a fully reusable launch system.” According to Musk, a “Falcon 9 second stage will be upgraded to be like a mini-BFR Ship.” Musk later indicated that the modification will trial “Ultra light heat shield & high Mach control surfaces,” which SpaceX “can’t test well without orbital entry.” However, the upgraded upper stage “would not be used to test landings.” 
More Info (Space News)