Attached Link: http://www.skylighters.org/quad50/

Did more research. I was searching for M3. It seems the quad mount version had a different number, as Antonia Tiger said, M16. See the link for loads of pictures. Strange thing is that I looked at the manifests for the White motor company that made the M3A1 half track, and they showed none of this, but the internet claims that they were built by the White motor company, yet they show no record of them.

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