In any case in which gain has been realized but not recognized because of the provisions of subsection (a) (or so much of section
1031
(b) as relates to subsection (a) of this section), to the extent such gain is later recognized by reason of a disposition or redemption of an obligation received in an exchange subject to such provisions, the first sentence of section
1271
(c)(2) shall apply to such gain as though the obligation disposed of or redeemed were the obligation surrendered to the Government in the exchange rather than the obligation actually disposed of or redeemed. For purposes of this paragraph and subpart A of part V of subchapter P, if the obligation surrendered in the exchange is a nontransferable obligation described in subsection (a) or (c) of section
454—