If you're gonna insist on "out of date" stuff for the Snake Eaters, the M151 "Mutt" was gradually being replaced by the HMMWV the mid-Eighties.
http://www.them151mutt.com/
If the US Government really, really believes there is going to be an atomic war with the Soviet Union within 5 years, 10 years at most ... are they going to make presumably-expensive cryoberths, staffed with some of the nation's best-trained soldiers ... and then allot them some left-over WW2 equipment? Especially if "possibly fighting the Morrow Project" is the Snake Eaters' purpose? The government has to have noticed the Project has modern armored cars and modern small arms.
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Michael B