2 to 2 1/2 pounds grapefruit per quart
Wash grapefruit: drain. Peel grapefruit, cutting deep enough to remove white pith. Run a knife between pulp and membrane of each section; lift out the pulp without breaking the cell structure. Discard seeds. Make a light syrup; keep syrup hot. Pack grapefruit into hot jars, leaving 1/2 inch headspace.
Ladle hot syrup over grapefruit, leaving 1/2 inch headspace. Remove air bubbles. Adjust two-piece caps. Process pints and quarts 10 minutes in a boiling water canner.
I am sure you could do oranges the same.
I also found how to freeze them.
Select firm, tree-ripened fruit. Heaviness of fruit indicates maturity. Wash fruit; chill in refrigerator; peel; section fruit, removing all membranes and seeds.
Syrup pack- Prepare a medium syrup. Add 1/2 teaspoon ascorbic and citric acid mixture to the syrup. Pack fruit into can-or-freeze-jars or plastic freezer boxes. Ladle syrup over fruit, leaving 1/2 inch headspace. Seal, label, and freeze.
Note: Grapefruit juice may be used in place of part or all of the water in the syrup.
Medium syrup recipe-
3 1/4 cups sugar
5 cups water
Cook until all sugar is dissolved. Makes 7 cups
I got these recipes out of my favorite book "The Ball Blue Book Guide to Home Canning, Freezing and dehydration". This book is found in most grocery stores!