CFR›Title 49›Subtitle B›Chapter VI›Part 663 ContainsSubparts A–DCorpusDaily eCFRDisplayed edition2026-04-23Last updated2026-04-23 PART 663—PRE-AWARD AND POST-DELIVERY AUDITS OF ROLLING STOCK PURCHASES Subparts A Subpart A—General Sections 663.1–663.15 B Subpart B—Pre-Award Audits Sections 663.21–663.27 C Subpart C—Post-Delivery Audits Sections 663.31–663.39 D Subpart D—Certification of Compliance With or Inapplicability of Federal Motor Vehicle Safety Standards Sections 663.41–663.43 Authority49 U.S.C. 1608(j); 23 U.S.C. 103(e)(f); Pub. L. 96-184, 93 Stat. 1320; Pub. L. 101-551, 104 Stat. 2733; sec. 3023(m), Pub. L. 109-59; 49 CFR 1.51.Source56 FR 48395, Sept. 24, 1991, unless otherwise noted. Previous 661 Part 661—Buy America Requirements Next 665 Part 665—Bus Testing