Plunder Road (1957)

On a dark night of pelting rain, five men stage a well-planned train robbery and get away with a $10 million, nine-ton gold shipment. Dividing the massive haul into three concealed truck loads, the team makes a would-be inconspicuous escape across country to what they hope will be a perfect getaway.

IMDb: https://www.imdb.com/title/tt0050847