samba - Nov 2010 - The least possible Samba client version able to work with Samba 3.5.6 server

Hello,

We have to work with a number of old OS; the problem is to find out what 
minimal Samba version is required to make a client work with a server 
running Samba 3.5.6.

In my experiments I had to use at least Samba 3.3.*, but if there are 
use cases for much earlier versions, I'd be glad to know of them.

Thanks in advance.
Sincerely,
Konstantin