Spread 4 to 6 c. of sliced fresh peaches in a 9x13 pan (don't grease.) Mix 1 ½ c. Splenda® Blend and one small box of dry peach gelatin together and spoon over the peaches. Using one regular size box of white or yellow cake mix, sprinkle it dry over all the peaches. Next, pour 1 c. hot (not boiling water) over the cake mix. Sprinkle 6 T. melted margarine over the cake. Bake at 350 degrees for an hour or until cake is light brown. Serve with Cool Whip® or ice cream.