1. A METHOD FOR FABRICATING AN AUTOMOBILE SIDE RAIL HAVING A HOLLOW RECTANGULAR CROSS SECTION FROM A CONTINUOUS PLANAR STRIP METAL STOCK, SAID STRIP METAL STOCK HAVING LONGITUDINALLY EXTENDING MARGINS, SAID METHOD COMPRISING THE STEPS OF ROLLING SAID STRIP METAL STOCK SO AS TO INTEGRALLY FORM ON ONE SURFACE THEREOF TWO LONGITUDINALLY EXTENDING PORTIONS OF A THICKNESS HEAVIER THAN THE REMAINING PORTIONS OF SAID STRIP METAL STOCK, SAID LONGITUDINAL PORTIONS OF HEAVIER THICKNESS BEING LATERALLY SPACED FROM EACH OTHER AND FROM THE MARGINAL EDGES OF SAID STRIP METAL STOCK, EACH PORTION OF HEAVIER THICKNESS