Very large very slow moving triangle shaped craft, no sound east bound over B-line Expswy between Orlando& Cocoa Bch , June-July 1975

Approx. june-july 1975 heading west on 528 (b-line expressway) 1:00-3:00am approx 1/2 way from Coco Beach to Orlando  myself & passanger encountered 3 large very low flying triangular shaped objects. They flew over us in a southeast path. One almost directly over us with NO sound, almost like a "cartoon image" moving very slowly. 
No traffic was moving in our direction but 3 cars were stopped accross the highway in the east direction. 
People were standing outside looking up about 1000' away from us. 
Lights flashing from white to light blue with some dark red areas. They were clearly visable for 5 to 7 minutes.
Although we were young and open minded at the time, because of the intensity of this encounter, our conversation was limited for the remaining trip. 
We called Mcoy Airforce base that morning, they reported no experimental or any other flights in that area that night.
Witness indicates that date is approximate.  PD