the patches look like they may be LVT-H6, but being an old LVT mechanic, I would say that the patch is that of the LVTP5A1 and the weapon is the turret mounted 30 Cal air cooled machine gun. I have a similar patch for the LVTP7 that was given to me by the Royal Thai Marine Corps' Amtrac Bn when I was an instructor teaching a maintenance course in 1981.
Semper Fi and YAT YAS
Mike Dahlkamp
CWO-4 USMC (Ret)
1968-1998