Old 90 - Rear Axle Leak

Just failed MOT because of oil leak from rear axle showing on n/s drum backplate. I can vaguely recollect when i refurbed her last year that my old axle didnt have an oil seal which ran on the drive shaft as it showed in the Haynes pics, but simply relied on the inboard bearing lipseal which runs on the stub shaft - is this correct or is my old girl missing some bits?

thanks
steve