Courier

 is a Tier 5 Tank that upgrades from Stacker and Streamliner at level 60.

Design
The greatly resembles the Stacker but with two extra barrels on the end of each of its barrel stacks. Its large set of barrels now resembles a wider and compressed Streamliner, while its smaller set resembles a miniature Streamliner.

Technical
Being a Stacker branch, two barrels fire at once whenever it fires; one from each stack.