DINA Lohan, the leggy mother of Lindsay, is always described as a former Radio City Music Hall Rockette – but she’s not. After an inquiry from The Post, a spokeswoman for Radio City called back to say an exhaustive search found no record of Dina Lohan, or Donata Sullivan (her maiden name), ever being a Rockette. Execs at Cablevision, which owns Radio City, were said to be indignant anyone would claim to be a Rockette who wasn’t. “It’s like claiming to have a degree from Harvard when you don’t. It’s a big deal to be a Rockette,” said our source. A Google search of “Dina Lohan Rockette” yesterday turned up 884 links. Biographies of Dina, 44, also say the 5-foot-11½ blonde acted on the Broadway stage and in commercials – also apparently not true. “Look in SAG [the Screen Actors Guild]. Look in AFTRA [American Federation of Televison & Radio Artists]. Dina isn’t a member,” said a family source. “She never did a Broadway show. She never did ads.”