The MGB Realm MGB Late model Overdrive wiring with optional fuse images
Several MGB enthusiasts have recommended that an in-line fuse should be added to the shift lever mounted switch overdrive wiring. The insulation around the wiring tends to chafe and wear through repeated shifting. If the wire comes in contact with the surrounding metal a short will result and toast your wiring.
I initially chose to locate the fuse at the gearbox end. This is a mistake. Upon further analysis and advice, I have decided to add an addtional fuse at the point where the gearbox harness meets the main harness. The fuse will be closer to the source and therefore provide more protection. The fuse goes on the same circuit (white wire) as the fuel pump. I will also add an in-line fuse to the fuel pump as this circuit has none. Add a double bullet connector to the white wire, then place the fuses in-line to the white-brown wire to the gearbox and the white wire to the pump.
Please refer to the Technical  page for connections.