The citation is ambiguous. It may mean:
49 Stat. 543 (Pub. Law 74-255)
AN ACT To amend the Interstate Commerce Act, as amended, by providing for the regulation of the transportation of passengers and property by motor carriers operating in interstate or foreign commerce, and for other purposes - August 9, 1935 - 543
You can view this U.S. Statutes at Large citation at these source(s):
49 Stat. 543
U.S. Statutes at Large
PDF - https://govtrackus.s3.amazonaws.com/legislink/pdf/stat/49/STATUTE-49-Pg543.pdf
also:
We also found 1 parallel citation:
49 Stat. 542 (Pub. Res 74-45)
JOINT RESOLUTION To amend the public resolution approved June 28, 1935, entitled "Joint resolution providing for the participation of the United States in the Texas Centennial Exposition and celebrations to be held in the State of Texas during the years 1935 and 1936, and authorizing the President to invite foreign countries and nations to participate therein, and for other purposes - August 8, 1935 - 542
Link is to an internal page within a statute beginning on page 542.
You can view this U.S. Statutes at Large citation at these source(s):
PDF - https://govtrackus.s3.amazonaws.com/legislink/pdf/stat/49/STATUTE-49-Pg542a.pdf
also: