Vintage Sealtest Thermometer

Ive had this Thermometer in our Kicthen for awhile, My dad picked it up at a sale and I wanted it so we struck a deal ! It's made by Pam Clock Co. Inc. in New Rochelle NY. Made in the USA. I'm thinking late 60's early 70's....any help dating would be appreciated !! I'm just going by the picture of the Milk Carton.....wonder when they went to cartons from glass milk bottles???