I always thought the early Torker stems were all square backed but im sure i read somewhere (possibly the museum) that they did do round backs . Im also sure there is a Torker advert that shows a round back on a 6 bolt stem. My stamped Torker 6 bolt has a round back and we believe this was asian made in and around 84 so that fits with what Chris has said . The bike it came on was a true survivor bought from Alan's in Wigan around this time , no parts had been changed on it since new .
Im sure all the odyssey stems had chrome shafts .
Mike (Grab on kid) is the man to speak to , he know's his Torker stuff
Thinking about it , Mike did tell me the the threads are different ... ie imperial or metric . Just not sure which relates to which , i need to do a search for the thread .