Anglo-dunno if this can help track down the change in lyrics or not..
I have a Folkways album (1976) called "Heart Of Oak" recorded by a New York City group named "The X Seamens Institute".
Their lyrics are "...Jolly tars are our men.....".

Liner notes go on to say that:
   "Through the eighteenth century and into the nineteenth 'Heart of Oak' was the unofficial anthem of the British Royal Navy."