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# CATERPILLAR FINANCIAL SERVICES CORPORATION

POWERNOTES®

With Maturities of 9 months or more from Date of Issue

Registration No.  333-124310

Filed Pursuant to Rule 424 (b) (3)

PRICING SUPPLEMENT NO.  646                                                                   Trade Date:  09/12/05

(To Prospectus Supplement dated July 7, 2005 &

  Prospectus dated May 13,2005)                                                                    Issue Date:   09/15/05

The Date of this Pricing SupplementSeptember 12, 2005

SUBJECT TO REDEMPTION OR REPAYMENT

 CUSIP                                                                                                                                   Date and terms of redemption or

     or       Stated                                                                   Interest                                       repayment (includingany

Common  Interest                      Price to  Discounts &        Payment     Survivors                  applicable regular or special

  Code      Rate (1)   Maturity  Public (2) Commissions       Frequency       Option  Yes/No     record dates)

14911QJ77   5.05%           09/15/20        100%                2.12%              Semi-Annually              YES          YES               Callable at 100% beginning 09/15/08

                                                                                                                                                                                                                       and semi-annuallythereafter.                                                                                                                                        

                                                                                                                                                                                                                                               

                                                                                                                                                                                                                       

Principal                                                                                 1st Payment             Day         

Amount                  Proceeds                  Dealer                           Date                   Count

$424,000.00            $415,011.20            ABN AMROInc.        03/15/06                              30/360    

Original Issue DiscountNote:                                                                          Total Amount of OID:

____  Yes                X   No                                                                                  N/A

The interest rates on the PowerNotes® may be changed by Caterpillar Financial Services Corporation from time to time, but any such change will not affect the interest rate on any PowerNotes® offered prior to the effective date of the change.  After the issuance of the PowerNotes® covered by this

Pricing Supplement, $936.150 mm principal amount of PowerNotes® remain available for sale

pursuant to the accompanying Prospectus Supplement.

Expressed as a percentage of aggregate principal amount.  Actual Price to Public may be less, and will be determined by prevailing market prices at the time of purchase as set forth in the confirmation sheet.