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”
EOS Digital Rebel XT:
Body No. “0310100001 – 0310112966”, “0320100001 – 0320105992”, “0330100001 – 0330127407”
The body number becoming faint or wearing off does not affect the product functionality. It also does not affect warranty service since the body number is recorded as data in the product. Please contact your local service center if you encounter this problem.

Read the full details here.