I have finally manged to make contact with Electrex world.
The regulator you require is their RR33 Regulator/Rectifier. You will probably notice the combined unit has 7 wires whereas the original units only had 6 wires. Also the plug configurations are different. None of this matters technically but you will need to modify as follows.
The original Rectifier has 3 yellow wires, one for each phase. These need to be connected to the 3 white wires from the combined unit. There is no specific order.
The Green, Brown and Black wires on the combined unit connect to the Green, Brown and Black wires where the Original regulator plugged into the main wiring Harness.
You will now be left with a single Red wire, the extra 7th wire. This needs to be connected to the Battery Positive either directly or into a positive line in the main wiring harness.
In summary the 3 white wires are for the 3 phases of charging. The Green and Brown wires are for the Field Coil and the Black and Red wires are for the Battery.