A Lycoming model O-540-J2B5D engine should have which magneto(s) installed?

The correct answer is based on the specifications and compatibility of the Lycoming model O-540-J2B5D engine with the appropriate magnetos. For this particular engine, the installation of Bendix D6LN-3230 magnetos aligns with the manufacturer's guidance and operational requirements.

The Bendix D6LN-3230 magnetos are specifically designed for the O-540 series and ensure optimal ignition performance under various operating conditions. They are compatible with the engine's design, providing reliable start-up and power generation, which is critical for ensuring the engine functions smoothly and efficiently.

In contrast, the other magneto options, while potentially suitable for other models or configurations, do not meet the specific requirements set forth for the O-540-J2B5D engine. Using the incorrect type of magneto can lead to ignition issues, decreased performance, and could even cause operational safety hazards. Therefore, choosing the Bendix D6LN-3230 magnetos is the correct decision based on both manufacturer recommendations and the operational integrity of the engine.