Z900A4 emulsion tubes o ring

Can anybody clarify if the emulsion tubes on a Kz/Z900A4 should have an o ring.
None of mine have and I cant see any in the parts list but some carb kits come with them and some other bikes that use similar carbs seem to have them.

Nessism, or Zed1015 will know better. As I know it the early Kz900 Carbs with the rubber cover on the choke lever don’t use an ORing. All (most) use an ORing with a different main emulation tube. The early Kz900 on the left 

 

The versions that take the O-ring typically have a distinct groove in the emulsion tube, above the threads and below the hex.

This photo shows the type that take the O-ring.

 

Thanks guys. Mine has the thread all the way up so confirms with being a 76 model without an o ring.
Just wanted to be sure before putting them back on the bike.