N.Y. Pers. Prop. Law § 314

§ 314. Security interest in other property. No retail instalment\ncontract, or any other agreement executed in connection therewith, shall\nprovide for the creation of a security interest in any personal or real\nproperty, other than the motor vehicle which is the subject matter of\nthe retail instalment sale (or accessories therefor or special or\nauxiliary equipment used in connection therewith), to secure the payment\nof the time sale price under such contract or any part thereof,\nprovided, however, that the prohibition of this section shall not be\napplicable to the taking of a mortgage or other security interest upon\nor in connection with real property to secure the payment of the time\nsale price of a retail installment sale, if the subject matter of the\nretail installment sale is a mobile home or trailer which is to be\nannexed to or situated on such real property. Any such prohibited\nprovision shall be void but shall not otherwise affect the validity of\nsuch contract.\n