The rear brake appears to be a SunTour XC Sport rollercam. Normally, you'd expect to find SunTour derailleurs and SunTour/Sugino cranks with that. I could see a derailleur upgrade for SIS but the front Shimano cantilvers make it a bit puzzling. A frankenbike? Or maybe a Diamondback? Circa 1986, they mixed groups, had chainstay mounted spoke carriers, low-rider mounts on the forks and a celeste paint scheme. Is that front derailleur a Deore XT? What's the serial number?