Put giblets and neck in large stock pot filled 3/4 the way full (one gallonish) and cook down for 1 1/2 hours just under boiling.
Remove neck and giblets from broth. Set aside one cup liquid to cool for slurry. (Now is when I also take out 1 to 2 cups to use as my broth for stuffing)
After turkey has cooked add drippings to broth. Mix flour and cooled reserve broth in shaker or whisk until smooth. (If the broth is not cooled and you are using a gravy shaker the mixture will expand and possibly explode)
Add slurry to broth and cook until desired thickness. Add salt and pepper to taste. You can add more flour to thicken if necessary. Serve over turkey and potatoes!