All of the DCM USGI 30-06 ammo that I purchased in the 80s and 90s came in USGI ammo cans that were vacuum sealed at the factory when it was made. It was mostly LC'69 and LC'68 vintage, but all of it was vacuum sealed.

I have read that you should NOT put desiccant packages into sealed cans of ammo because it can pull the moisture from the priming compound in the primers, making it less likely to go bang.