When I go to Stages and Jobs > Default Stage > Default Job > Tasks > Add Task > Nunit Runner > Executeable
My options are: Nunit 2.6.4 and also the x64 and BO4.2 versions of the same. There is no NUnit 3.X. I understand this was an issue in some older versions of Bamboo. I'm running Bamboo 6.5 build 60509.