I just got a Chevrolet Dealer Ordering Guide for the 1977 model year. There is some interesting information to be found in here but something popped up right away.
Taken from Issue #26 of the Louisville Zone Distribution Newsletter, dated May 6, 1977
MONZA MIRAGE COLOUR AVAILABILITY
In response to many field requests for additional colour choices on the Monza Mirage, Michigan Automotive Techniques Inc. has informed us that effective immediately the following new colour combinations can be ordered:
Exterior Paint Colour Code
Lower....Upper....Body Colour....Stripe Colour
13........13........Silver...........Dark Red Metallic
19........19........Black...........Gold
75........75........Light Red......Gold
To obtain any of the new combinations, simply insert the desired colour code on the Chevrolet Order Form. Stripe Colour is automatically determined by the body colour as shown on the chart above. The actual stripe design remains the same as contained in the original red, white and blue colour scheme which is still available. Any interior compatable with the new colours may be ordered.