I also flew on Icelandair well before my memory permits.
My family was moving to Germany in 1974 for two years because my Dad got a NATO fellowship. At that time, there were very few "bargain" transatlantic carrier.
My parents opted to take Icelandair, then called Loftleider Icelandic from New York JFK
through Iceland to Luxembourg in order to get to Europe.
I was only nine months old and my Mom had to sit with me in her lap. The plane out of JFK
was delayed 8 hours and when they landed in Rejkyavik, it was sleeting. As Loftleider didn't have the nice terminal that Icelandair has now, the flight attendant gave my mom a blanket to wrap around me as they walked down stairs and over to a converted airplane hanger to wait for the outbound flight to luxembourg.
The aircraft was a DC-8-63.
You undoubtedly flew a DC-8-73 as Icelandair had its aircraft converted to the larger turbofans in the 1980s.