BANK OF MONTREAL LOAN AUTHORIZATION AGREEMENT DATED: FEBRUARY 13, 2008

Exhibit 10.13

BANK OF MONTREAL LOAN AUTHORIZATION AGREEMENT

DATED: FEBRUARY 13, 2008

The Company referred to below has applied for, and Bank of Montreal, Chicago, Illinois (“Bank”), has approved the establishment of, a loan authorization account (“Loan Account”) from which the Company may from time to time request loans up to the maximum amount of credit shown below (the “Maximum Credit”) provided that the aggregate principal amount of loans hereunder shall not exceed $370,000,000. Interest on such loans is computed at a variable rate which may change daily based upon changes in the Bank’s Prime Rate. The Company may make principal payments at any time and in any amount. The request by the Company for, and the making by the Bank of, any loan against the Loan Account pursuant hereto, shall constitute an agreement between the Company and the Bank as follows:

Amount of Maximum Credit: $370,000,000

Each Loan Requested Shall Be At Least: $100,000

Periodic Statement reflecting accrued interest will be sent and interest will be payable quarterly.

If Letters of Credit may be requested, check here: ¨ and attach Letter of Credit Rider following signature page hereof.

Loans will be made available from the Loan Account subject to the Bank’s approval on a case-by-case basis as and when Loans are requested by the Company.

All Loans shall be made against and evidenced by the Company’s promissory note payable to the order of the Bank in the principal amount of $370,000,000, such note to be in the form of Exhibit A attached hereto (the “Note”). The Bank agrees that notwithstanding the fact that the Note is in the principal amount of $370,000,000, it shall evidence only the actual unpaid principal balance of Loans made under the Loan Account and issued pursuant hereto. All Loans and other extensions of credit made against the Note and the status of all amounts evidenced by the Note shall be recorded by the Bank on its books and records or, at its option in any instance, endorsed on a schedule to the Note and the unpaid principal balance and status and rates so recorded or endorsed by the Bank shall be prima facie evidence in any court or other proceeding brought to enforce the Note of the principal amount remaining unpaid thereon, the status of the Loans and other extensions of credit evidenced thereby and the interest rates applicable thereto, absent manifest error; provided that the failure of the Bank to record any of the foregoing shall not limit or otherwise affect the obligation of the Company to repay the principal amount of the Note together with accrued interest thereon. The Bank agrees that if it transfers or assigns the Note, the Bank will stamp thereon a statement of the actual principal amount evidenced thereby at the time of transfer. The Company agrees that in any action or proceeding instituted to collect or enforce collection of the Note, the amount shown as owing the Bank on its records shall be prima facie evidence of the unpaid balance of principal and interest on the Note, absent manifest error.

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(i) Unless the Company notifies the Bank that the Company intends to pay the interest due on the Loans on each Interest Payment Date with funds not borrowed under this Agreement, the Company shall be deemed to have irrevocably requested a Loan on each Interest Payment Date in the amount of the interest then due on the Loans, in each case subject to the provisions of this Agreement (other than the requirement that a Loan be in a certain minimum amount), which new Loan shall be applied to pay the interest then due on the Loans. In the event the Company has elected to pay the interest due on the Loans with funds not borrowed under this Agreement and the Company fails to make any such payment within twenty (20) days of the applicable Interest Payment Date the Bank may in its sole discretion deem the Company to have irrevocably requested a Loan in the amount of the interest then due on the Loans, in each case subject to the provisions of this Agreement (other than the requirement that a Loan be in a certain minimum amount) which new Loans shall be applied to pay the interest then due on the Loans.

(ii) Each payment of interest by a borrowing of a Loan shall be evidenced by the Note, shall bear interest from the date made at a rate per annum equal at all times to the rate then applicable to the Loans, payable on the last day of each calendar month, subject to the provisions of paragraph 10 herein.

(iii) In no event shall the unpaid principal balance of all Loans, including, without limitation, each borrowing of a Loan to pay interest then due on the Loans, exceed the Maximum Credit.

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During the existence of any Event of Default, the Bank may, by notice to the Borrower, take either or both of the following actions: (i) terminate the Loan Account and any other obligation of the Bank to extend any further credit hereunder on the date (which may be the date thereof) stated in such notice; and (ii) declare the principal of and accrued interest on the Loans and all other amounts owing under this Agreement to be immediately due and payable, without further demand, presentment, protest, or notice of any kind.

When any Event of Default described in clause (e) or (f) above regarding the Borrower has occurred and is continuing, then both principal and interest, and all other amounts payable under this Agreement shall immediately become due and payable without presentment, demand, protest or notice of any kind, and the obligation of the Bank to extend further credit pursuant to any of the terms hereof shall immediately terminate.

No delay by the Bank in the exercise of any right or remedy shall operate as a waiver thereof, and no single or partial exercise by the Bank of any right or remedy shall preclude any other or further exercise thereof or the exercise of any other right or remedy. The Borrower agrees to pay to the Bank all reasonable out-of-pocket costs and expenses incurred or paid by the Bank in connection with the collection of the Loans and any other amounts due under this Agreement or any guarantee, including, without limitation, reasonable attorneys’ fees for one outside counsel for the Bank and court costs (including, without limitation, all such costs and expenses incurred in connection with any proceeding under the United States Bankruptcy Code involving the Borrower or any guarantor). The Bank shall have the right, at any time during the existence of an Event of Default, to set-off the balance of any deposit account that the Borrower may at any time maintain with the Bank or any of its affiliates against any amounts at any time owing under this Agreement, whether or not the balance of Loans under this Agreement is then due.

(a) as soon as available, and in any event within 30 days after the last day of each month, a copy of the consolidated balance sheet of the Company and its subsidiaries as of the last

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day of such month and the consolidated statements of income, retained earnings and cash flows of the Company and its subsidiaries for the month and the fiscal year-to-date period then ended, each in reasonable detail showing in comparative form the figures for the corresponding date and period in the previous fiscal year, prepared by the Company in accordance with general accepted accounting principles (“GAAP”), except as otherwise stated therein, and certified to by its chief financial officer or such other officer reasonably acceptable to the Bank; and/or

(b) as soon as available, and in any event within 90 days after the close of each fiscal year of the Company, a copy of the consolidated and consolidating balance sheet of the Company and its subsidiaries as of the close of such period and the consolidated statements of income, retained earnings and cash flows of the Company and its subsidiaries for such period, and accompanying notes thereto, each in reasonable detail showing in comparative form the figures for the previous fiscal year, accompanied by an unqualified opinion thereon of a firm of independent public accountants of recognized national standing, selected by the Company and reasonably satisfactory to the Bank, to the effect that the financial statements have been prepared in accordance with GAAP and present fairly in all material respects in accordance with GAAP the consolidated financial condition of the Company and its Subsidiaries as of the close of such fiscal year and the results of their operations and cash flows for the fiscal year then ended.

No delay by the Bank in the exercise of any right or remedy shall operate as a waiver thereof, and no single or partial exercise by the Bank of any right or remedy shall preclude any other or further exercise thereof or the exercise of any other right or remedy. The Company agrees to pay to the Bank all reasonable expenses incurred or paid by the Bank in connection with the establishment and maintenance of the Loan Account

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and the collection of the Loans and any court costs and other reasonable amounts due under this Agreement, including, without limitation, reasonable attorneys’ fees. The Bank shall have the right at any time to set-off the balance of any deposit account that the Company may at any time maintain with the Bank against any amounts at any time owing under this Agreement, whether or not the balance of Loans or reimbursement or other obligations under this Agreement are then due.

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The Company agrees to the terms set forth above.

This Agreement is dated as of the date first written above.

This Agreement is dated as of the date first written above.

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