Hi Ray,
those were Air vietnam Bristol Freighter, several of them were requisition, they were used to carry dismantled M24 15-ton light tank to Dien Bien Phu.
not much information, exepted these entries
http://www.crash-aerien.com/www/database/fiche.php?id=9827
http://1000aircraftphotos.com/Contributions/Alfarrabista/4333.htm
cheers,

Olivier