Green’s Dictionary of Slang

(US tramp) fast, e.g. a rambling freight.

1962		Ragen & Finston World’s Toughest Prison 814: rambling – Travelling at high speed.
a.1968		‘The Days of Forty-Nine’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 180: A bummer, too, they call me now, / But what care I for praise? / And as I flit from town to town / They call me the rambling sign / Of the days of old and the days of gold.
1970		B. Jackson Get Your Ass in the Water (1974) 58: Now Dolomite was from San Antone, / a rambling skipfucker from the day he was born.