As the operational demands of liquid rocket engines increases, so too does the need for improved design and manufacturing methods for metal-to-composite nozzle extensions. The state of the art utilizes non-domestic composite materials for nozzle extensions. Although this solution does offer weight savings and increased performance, there is an increase in cost and the addition of Export regulations. Within this effort, Materials Research & Design (MR&D) is proposing an analytical study, coupled with subcomponent fabrication and testing, that would result in a design for a domestically available C-C nozzle extension and metallic-to-composite joint for the J-2X. The proposed study would investigate various mechanical attachment methods, such as mechanical fasteners and adhesives for both the CMC-to-metallic joint and the CMC-to-CMC joint. Additional aspects of the trade study would investigate various flange shapes and materials in order to reduce the critical stresses in the region.