An optical transceiver includes a transceiver housing configured to receive an optical sub-assembly insert. The optical sub-assembly insert includes duplex cavities configured to hold a transmit optical sub-assembly front end and a receive optical sub-assembly front end in a fixed spatial orientation for a given optical connector interface. The optical sub-assembly insert is configurable to fit inside a transceiver housing with a relatively wide range of X and Y dimensional tolerance. In one implementation, the X-Y position of the optical sub-assembly insert is dictated by the position of the transmit optical-sub assembly front end after its corresponding back end has been mounted to a heat dissipation element. Any gaps that form between the optical sub-assembly insert and the inside surface of the transceiver housing as a result of the transmit optical sub-assembly position can be accommodated with filler material.