Oliver Delehunty 1960's was from Dublin at that time any way to research it? He was in his 70's

The surname "Delehunty" is recorded as "Delahunty" in Ireland, mainly - 1901 Irish Census.

You will need to get further information as to how they arrived in the USA, whether by Ocean liner, or Airline.

Regards,

Here’s an Oliver Delahunty born in Dublin in 1920.  (So if it’s the right person, he’d have been in his 40s when he visited the US, not his 70s). I don’t see any earlier Oliver births:

https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_returns/births_1920/01209/1502636.pdf

Parents Joseph Delahunty & Anastasia Maher married in 1919 (spelled Delahoyde then):

https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1919/09685/5512710.pdf

Family in 1911:

http://www.census.nationalarchives.ie/pages/1911/Dublin/Mountjoy/Richmond_St__North/15960/

Same family in 1901:

http://www.census.nationalarchives.ie/pages/1901/Dublin/Mountjoy/Upper_Gloucester_Street/1328797/

Parents marriage in 1892:

https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_re…

You say............
Oliver visited some cousins in Iowa back in the mid 1960's and he and his wife, don't know her name, were in their 70's 

What are the names of the cousins?
I have searched for Oliver on the travel records and have not seen him listed.