Those rotary gondola 2-packs and 4-packs first appeared in 2016 Volume 2. Understand they were on the production schedule at the Romanian factory at which tooling issues arose with the long-awaited milk cars (per Mike Reagan) . Catalog said paint schemes for the 4-packs would match previously released rotary gondolas, presenting an additional manufacturing challenge.
Ordered a 6-84010 4-pack in September 2016. Not holding my breath but may stop breathing before the gondolas are shipped.