Tungsol 5881's

I've got a Supratek pre with 5881's and haven't gotten around to rolling out the Sovteks (arrghhh!! groans from the gallery...).

Yes, Tungsols, and yes brown bottom, but what iteration?

I see references to double D getters, short bottles, some that appear to be JANs etc.

What do I need to get/ stay away from?

Please, educate me!!

Thanks,

Mark