Uncle Fletcher was always going way overboard on his gifts. There were times when he sent three fierce bulldogs; on at least two occasions he had gigantic doorstops made out of railroad track pieces that weighed over 400 pounds to give away as gifts; another time he presumably spent $1000 or more on Mr. Gumpox for a harness for his horse -- and this is where we gather the information for this presumed episode.
[There were many other incidents along this vein as well that I have not mentioned.]
We don't know if this episode actually existed or not but 20/20 vision shows us that most things spoken about the family did indeed take place in an episode. Either way, we can be assured that the generous Uncle Fletcher did indeed at least try to send eleven barrels of oysters to Vic, Sade and Rush.
We can also assume the conversation that took place after finding out the news: imagine the smell of the other ten rotting barrels? Where would the Gooks keep the oysters? And other such nonsense.
The date of this episode had to have happened before 1941, since this was spoken of on the last day of 1940.