I know this lense does not autofocus on the D40 or D40x, but it will on a D80. What about the D70s?

 

yes, any nikon lens will work on older cameras.

 

Yes, the D-70 will auto focus the lens. The D-40 is the one-off.

 

anyone know where I can still find a D70?

 

That might be hard. I found my D70s by luck at a Ritz Camera. They didn't have it on display and I just happen to get in a conversation about it and found out they had one. You can see them in ebay. You also want to look in your local craig list.

 

Yes it does autofocus on the D70s

I have both of them and they work great together