The steel bevel gear back will be smooth (flat with amaybe a step) the sintered will have ribs on the back, or what looks like teeth and olders ones even had first gear made to it.
As for oil seaping out thru bushings or around use rtv lightly in the bushing cvaties and when installed they are sealed there as for between the shaft and bushing thats not enough to worry about AND thats why we only use the small amount of oil. Just enough to get the job done.