Editorial Notes Codification Section, Pub. L. 90–448, title IV, § 408 , Aug. 1, 1968 , 82 Stat. 516 ; Pub. L. 91–609, title III, § 303(c) , Dec. 31, 1970 , 84 Stat. 1780 , which related to incontestability of guarantees was omitted pursuant to section 4528 of this title , which terminated authority to guarantee bonds, debentures, notes, or other obligations under this chapter after Dec. 31, 1970 , with exceptions now inapplicable.