Whats the difference between these cable modems?

[adl6009]

I saw these at buy.com and was wodering what the difference was and why would they have some 17 thousand of the office connect on hand. I mean that sounds like there must be something going on there. Take a look at my post http://www.sysopt.com/forum/showthread.php?s=&threadid=86908

Or check out these links
http://www.us.buy.com/retail/clearance/product.asp?sku=70002967&loc=13080

http://www.us.buy.com/retail/clearance/product.asp?sku=70003023&loc=13080

http://www.us.buy.com/retail/clearance/product.asp?sku=70003108&loc=13080

PS- I don't mean to cross post, but I thought the price was pretty good, I didn't have the time to really check out the modems today.