Welcome aboard Mario! Even Showcars Rob doesn't list them, for a Monza Coupe and I would avoid him unless you are near enough to him that you could bug him in person or
MAYBE, POSSIBLY eBay, even then, I found my personal experience with him to be somewhat painful as you would see with a quick Google/Yahoo search of others experiences. I didn't check to see if there were any "Sunbird" parts listed and I am unknowing if they would fit or not. Harry
You'd be better off to build your own than this: http://www.showcars-bodyparts.com/catalogue.html You have been warned!!
I'm not a hoarder I'm a preservationist 78 Monza Spyder (~Soon(ish +/- I guess) To Be 2+2 with Spoilers)