Will this plug straight into the factory connector?

Yes. This is a direct replacement — it uses the factory wiring harness without adapters or rewiring. Plug it in and you're done.

Do I need to remove the old light first?

Unclip or unbolt the original brake light from the mounting bracket, disconnect the connector, and install the LED unit in reverse. Basic hand tools only.

Will this work if my truck's electrical system is stock?

LED lights draw less power than halogen bulbs and work on factory wiring. No load resistors or additional wiring modifications are necessary.