Non le probleme provient des boitiers puisque les serial number sont ceux des boitiers:

April 15, 2005
We discovered that, for some of the EOS 20D and EOS Digital Rebel XT models that were produced during a certain period of time, the body number printed on the label had worn off following use of the product. This problem affects some products in the following serial number ranges:

EOS 20D:
Body No. "0910400001 - 0910402496", "0920400001 - 0920407771", "0930400001 - 0930417770"