This is a series of pictures of gondolas loaded with
containers pontoons on the New Haven.
Jack Consoli noticed the Navy Pontoon markings on them, and provided several links in the comments below. I'll leave my comments on container loads here.
There is a long article on container loads in this Freight Traffic Report, you'll need to go to pg 311 (the actual page number is 186) for the start.
Chapter 8 of this book is also very interesting, but it's a preview, so some portions are not available.
I'm not sure I recall seeing any in service photos of containers on the New Haven, so it was nice to get a small collection of them. They all seem to use the same types of containers, and one I haven't seen before. I don't know if these were purchased by the New Haven and these are outbound. Perhaps this is a record of a test. In any event, they are shown loaded into gondolas from several roads.
These first is a B&LE 36608, The 3rd number looks like a '6' to me, but could be an '8.'