My Mag lites are HB also. I used the 4 inch HB LED round truck tail lites and retrofitted them to the mag lites . Extremely visible day or nite now! Next addition will be an LED license plate lite. Heres a link to photos of how I converted them to LED.
Toad Magnetic LED lights - iRV2.com RV Photo Gallery
2003 34' Dolphin 5342, W22, UP, UPGBrake, F and R Track Bars, Rear IPD sway bar, Koni FSDs, Safe-T-Plus, Scan Gauge II.. 2004 Jeep Liberty, Blue-Ox Adventa..