Not really, here they are side by side: (Both are sales posts but I believe they are genuine, original examples. Heuer from Reddit and Sub from HQ Milton, who are a premier and extremely well-respected Rolex dealer in San Francisco) The first Heuer diver showed up in 1979 which was a popular year for getting into divers - the Timex Red Ball arrived that year as well, for instance - while the contemporary Submariner would have been the reference 5513. (The one shown here is an earlier example from the 1960s but it remained much the same throughout the '70s and even into the 80s). I wouldn't say it closely resembles the Sub at all, any more than the Submariner itself resembled the very first dive watches* from Zodiac and Lip-Blancpain released a year earlier. *yes the Turn-O-Graph debuted that same year, but it was not a dive watch.