As per our conversation at the Show 'n Shine, I'm pretty good with electrics also.
I searched the web for a diagram to confirm what I believe: that your charging system is a fixed magnet alternator type, where all the current going the wrong direction (half of the AC making it DC), and all DC Voltage over 14.5 volts gets dumped as heat through the nice aluminum fins on your new regulator/rectifier. The closest I got was a 1980 GS1000GT. All other years of other GS Suzukis confirmed the same.
The one thing Suzuki did that was fuggy was they did not have the three wires coming from the stator the same colour. The three wires on other bikes were often the same colour, often yellow or white. No big problem to figure out with a tester or just visually looking. The 1980 GS1000 wiring diagram shows them as G/W W/Br and Y (green with white tracer, white with brown tracer, and yellow).
If your new reg/rec is a universal one for these types of alternators, it
probably has three wires the same colour, often all are yellow or white. These three and three go together in any order.
There should be a ground which is universally black, and often has the tell tale eye hole attachment for grounding to the frame. The red is colloquially know as the "hot" and it usually goes to your main "on/off" switch, such that in the "off" position its not connecting with the battery.
The GS series has a notorious fault of burning out the charging system. A very lengthy, but very good read starts at this link called the "Stator Papers." By the end of it you'll be an expert on all the if/thens and whys.
http://www.thegsresources.com/statorpapers.phpI know you like to use existing wiring harnesses as much as possible. I really enjoy making or modifying wiring harness and would love to try one with some new wire connecting techniques I recently learned from Ted. Given all the help you've given me, I offer this in return.... 'cept this time you buy the beer.
Peace, Ohms, Watts & Volts, Dennis