I sourced the replacement 1" diameter 30" long solid live axle from a go kart vendor. The existing axle bearings were both 1" diameter. I looked for an axle with the differential but non exist in this length. Neither is there any space for the differential because of the trunk. Differential axle would also call for two disc or other brakes on its each end.
Next I looked into a custom aluminum sprocket to cut weight. The stock drive sprockets weighs a whopping 5 lbs 7.2 oz. The custom cut sprocket with mounting hub weighs 1 lb 15.7oz.