regulator/rectifier

[beermaker]

My reg/rectifier appears to be paggered (technical term from oop north!) I've been running on battery alone for about six weeks but the dark nights/mornings mean I'm cutting it fine getting home now! I have a reg/rectifier off a Suzuki GS500 - difference is that it has five terminals, not six. Looking at the diagrams it appears that the GS unit has the three alternator connections and the connections for live and neutral to the battery, but not the connection which appears to go to the headlight/tail light fuse. Does that matter and if not, can anyone think of a valid reason why I can't use the GS500 unit rather than fork out for the ZXR one?