(3) The Agency shall provide assistance under this subpart to a displaced person who is not eligible to receive a replacement housing payment under §§ 24.401 and 24.402 because of failure to meet the length of occupancy requirement when comparable replacement rental housing is not available at rental rates within the displaced person's financial means. (See § 24.2(a)(6)(viii)(C).) Such assistance shall cover a period of 42 months.