1947-50 3/4-ton drums are impossible to find NOS and I am not aware of any new manufacturing of them. I bought another early truck just for these items recently for my own spares. I lucked out by getting 3 good drums plus a full set of near new shoes. I know the change you are contemplating has been done by others for similar reasons. It is not difficult if you have a donor set-up and the later style drums are widely available though they are not cheap. If you do change I would recommend all new u-bolts it is cheap insurance on 60+ year old parts.
