I googled Sealtest and was not able to find out much. Apparently a company by the name of Natel has the rights in Canada except it seems that they do not do ice cream but they do a lot of other dairy products. It seems that they do not market in the USA.
It seems that everything Sealtest is for sale for people collecting antique things.
Sealtest had good ice cream back in the early 50's but the it was about all we had except Pet and I did not know any different. I thought all ice cream was good back then
I will always remember "Under the Bigtop" on Saturdays which I was only about 7-8 years old. That was 55 years ago. I sure did enjoy TV then.
Paul E. Smith