Section 43 of this title, relating to deposit requirements, and section 45 of this title, relating to prepayment penalties, shall not apply and the parties may contract for a rate of interest in excess of the rate provided in section 41a of this title in the case of:
(1) obligations of corporations, including municipal and nonprofit corporations; or
(2) obligations incurred by any person, partnership, association, or other entity to finance in whole or in part income-producing business or activity, but not including obligations incurred to finance family dwellings of four units or fewer when used as a residence by the borrower or to finance real estate that is devoted to agricultural purposes as part of an operating farming unit when used as a residence by the borrower; or
(3) obligations to finance the purchase, construction, or improvement of property for seasonal or part-time occupancy and not as a place of legal residence; or
(4) obligations guaranteed or insured by the United States of America or any agency thereof.