In 1981, the Betty Crocker Supreme Fudge Brownie Mix included a 5.5 oz can of Hershey's syrup. In 1949 you could get a 5 oz can when you purchase 2 quarts of ice cream. https://archive.org/details/mansfield-news-journal-1949-08-1...

It came in multiple sizes. 5 oz is probably the "small can" mentioned at https://archive.org/details/trinity-parish-of-newton-centre/... .

There was also a 16 oz can, https://archive.org/details/escanaba-daily-press-1964-12-10/... and https://archive.org/details/childrenasconsum0000mcne/page/11... and https://archive.org/details/The_Times_News_Idaho_Newspaper_1... and https://archive.org/details/cupl_004738/mode/2up?q=%22can+of... .

And an 8 pound can (!) for food services. https://archive.org/details/foodloversguidet0000harr_d5o7/pa...