I recently acquired an M170 still in its military colors. The stencils are fairly easily read, but I am curious about this one's unit. I've done a quick search of meanings, but can't get a clear answer from the web. The unit information is as follows:
33BO-I-153 HQ-54
My question is, what does the "BO" mean? I've not seen it before. Any help would be appreciated.