1. Open and remove ham from package and rinse. Put in large zipper sealed gallon plastic bag.
2. In large bowl combine syrup from pineapples (reserve pineapple slices for baking) and brown sugar. Mix should be very thick. Add mix to bag with ham and marinate in fridge overnight.
3. To Bake: Preheat oven to 350 degrees F. Place ham and mix into a large baking pan with deep sides to avoid spillage in oven. Place pineapple slices on ham so they overlap each other and pile on top what's left.
4. Cover with aluminum foil and bake for 1 hour. Take off foil and bake an additional 20 minutes. Remove pineapples and serve separately. Very tasty. Slice ham for serving.