Christie Brinkley And John Mellencamp -- Downtown Date Night (PHOTO)

Christie Brinkley is still with the band.

The uptown girl had dinner with rocker John Mellencamp Monday night in downtown Manhattan ... fueling rumors they've hooked up.

She's hasn't been linked to anyone since 2008 when she divorced her 4th husband. Mellencamp recently broke it off with longtime GF Meg Ryan and also has 3 marriages under his belt ... so lots in common to talk about at dinner.