We have genuine Suzuki OEM gaskets for the Clutch Cover of your Suzuki DR-Z400.
 
This is the inner gasket for the clutch cover case (see picture for location). This gasket can be damaged easily when you remove the clutch cover from the engine block.
 
You'll either be lucky and remove the cover without tearing it apart or unlucky and you will need to remove the old gasket and install a new one.
 
So it's a good idea to have a gasket handy before you start removing the cover, just in case you are unlucky with it!
 
This is a Suzuki Genuine Parts:
11482-29F00-000 GASKET, CLUTCH COVER
 
Note: We also have the outer clutch cover o-ring available here:  Clutch Cover O-ring