The first box that decided to open has a label - US 87th Infantry. I seem to remember giving regimental numbers according to scale. There should be boxes for 87th, 76th, 72nd etc.
This box contained Airfix first type US marines, which came as a surprise, as I thought I had already found these and based them. Here are the contents:
Last night I finished off basing them and when added to the original battalion painted last week I have a sizable force, which I will call a brigade:
Amongst this group are some interesting conversions. First off there are two 37mm? anti-tank guns with converted crew: