for establishing fair market value for guaranteed investment contracts and investments purchased for a yield restricted defeasance escrow. The provisions of sections 1.148-5(d)(6)(iii) (relating to the safe harbor for establishing fair market value of guaranteed investment contracts and yield restricted defeasance escrow investments) and 1.148-5(e)(2)(iv) (relating to a special rule for yield restricted defeasance escrow investments) may not be applied to any bond sold before December 30, 1998.