Place 8 1/4 cups of sliced trimmed cucumber slices in a large glass or stainless steel bowl. Set aside.
Combine 2 cups white vinegar, 2 cups water, pickling salt, sugar and 6 tablespoons pickling spice in a medium stainless steel saucepan. Bring to a boil over medium-high heat, stirring to dissolve salt and sugar. Reduce heat, cover and boil gently for 10 minutes.
Pour pickling liquid over cucumber slices.
Cover with waxed paper and set aside until cooled to room temperature, about 30 minutes.
Place 1 1/2 teaspoon dill seeds, 1 teaspoon mustard seeds, 1/4 teaspoon peppercorns and two garlic clove halves in each of one five pint jars.
Add cucumber slices to within a generous 1/2-inch head-space of top of jar.
Ladle pickling liquid into jar to cover cucumbers, leaving 1/2-inch head-space.
Apply lids. For best results, allow cucumbers to marinate in refrigerator for at least 2 weeks and use within 3 months.