Well, the most important date isn’t necessarily the manufacture date. It’s the date of sale that really matters, since the laptop could have been manufactured and sat on a shelf for 6 months to a year before it was purchased.
IBM’s support site has a lookup tool, but it’s hard to find like everything else on their site.
Here is a link to the tool.
ok, looking at some other laptops that I have and checking the warranty lookup on IBM,
it seem that the date is at the end of the S/N, last 4 numbers
e.g S/N L3-HL576 07/04 (this laptop was manufactured in Apr 2007)
If you can prove that you purchased your laptop from an authorized distributor on a certain date, IBM will observe the warranty period from that day forward (as opposed to the date of manufacture, which may include transportation time and weeks / months on the shelf).