Finding the date of my Nikon lens?

I have a Nikon AF Nikkor 28-105mm f/3.5-4.5 D lens and I'm trying to find the manufacturing date of it. The serial # of this lens is 313xxx.

I'm sure Nikon has a list of the serial numbers and what dates they were manufactures, however you will have to contact Nikon for that information

The link below has a comprehensive listing of Nikon serial numbers, together with manufacturing dates and country, lens features and production run. According to this list, your lens was made somewhere between Dec. '98 and 2005.