A disclosed gas turbine engine includes a compressor section, a combustor section, a first turbine section and a second turbine section. An outer case structure for the gas turbine engine includes a single-piece case structure with a turbine case portion and a transition case portion. The transition case portion is integrally formed with the turbine case portion as a single part module. A combustor case houses the combustor and an aft turbine case supports the low pressure turbine. The outer case includes a forward end attachable to the combustor case and an aft end attachable to the aft turbine.