Guaranty: Ambac & Advanta Mortgage Loan Trust

As of November 17, 1999


Advanta Mortgage Loan Trust 1999-4 c/o Wilmington Trust Company, as Owner Trustee Rodney Square North 1100 North Market Street Wilmington, Delaware 19890-0001


Ambac Assurance Corporation One State Street Plaza New York, New York 10004


Re: Advanta Mortgage Loan Trust 1999-4
Sale and Servicing Agreement


Ladies and Gentlemen:


Pursuant to the Sale and Servicing Agreement dated as of November 1, 1999 (the "Agreement") among Advanta Conduit Receivables, Inc., as sponsor, Advanta Mortgage Corp. USA, as master servicer ("AMCUSA"), Advanta Mortgage Loan Trust 1999-4 (the "Trust"), Advanta Holding Trust 1999-4 ("Holding") and Bankers Trust Company of California, N.A. as indenture trustee (the "Indenture Trustee"), AMCUSA in its capacity as Master Servicer, has undertaken certain financial obligations with respect to its servicing of the Mortgage Loans, including, but not limited to, the making of Servicing Advances. In addition, the Sponsor has, in the Agreement undertaken certain financial obligations, including, but not limited to, the payment of the Loan Purchase Price relating to the repurchase of non-qualifying Mortgage Loans, the payment of Substitution Amounts in connection with the substitution of Qualified Replacement Mortgage Loans and the payment of certain expenses of the Trust. Any financial obligations of AMCUSA or the Sponsor under the Agreement, whether or not specifically enumerated in this paragraph, are hereinafter referred to as the "Joint and Several Obligations"; provided, however, that "Joint and Several Obligations" shall mean only the financial obligations of AMCUSA and the Sponsor under the Agreem ...