Sunline didn't start using the Saturn name, and only as a model designation, until 1986. Are you sure this is a Sunline? Do you have a picture?
That said, there is probably a VIN on the tongue somewhere, and possibly inside. I'll go into more detail once we determine if it's a Sunline or not.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR