Abstract: A gas turbine system combustor has an additively manufactured (AM) combustor body including a one-piece member having a plurality of parallel, metallurgically bonded metal layers in a transition portion of a combustion liner. An aft frame at an aft end of the transition portion has an inner end integral with the combustion liner partially defining a circumferentially extending passage and an outer end distal from the inner end. Circumferentially spaced ribs extend forward from the aft frame outer end on a transition portion exterior surface. A flow sleeve integral with the circumferentially spaced ribs has an aft end with a curved portion defining, with the aft frame inner end, a circumferential inlet to the circumferentially extending passage. The aft frame can be part of an AM aft frame structure with integral transition and flow sleeve portions that can be attached to the combustion liner and flow sleeve.