Yes. I'm sure they are perfectly OK. The ones we were getting back then had been stored in warehouses and dated as far back as WWII, the boxes had the dates. Some people didn't like them, but it was a matter of taste. Ham and Lima Beans were the least favorite, Not too many people liked the fruitcake, although I did. In all, the C's we ate were nutritious and well balanced. Later on, we got the freeze-dried packs which were pretty good except we often couldn't use them on patrols because water was scarce and you needed to add water to make them edible.
I remember some of the more industrious guys would make big pots of stews from C's, adding other ingredients including hot sauce.