An LED lighting system using a retro-formed component is disclosed. Embodiments of the invention make use of a component that has an external form factor of a structural element of a pre-existing light fixture. The component, for example, can be a power supply, or a heat sink with a connector. The component allows an LED lighting unit to be used without having the power supply and/or a heat sink take up space within what a consumer would normally see as the light bulb. In some embodiments the form factor is that of a screw-in socket such as an Edison E-26 socket. A connector or connectors can allow removal of the power supply portion of the lighting unit, or of the LED and possibly an optical element from the power supply.