1973 914, what is a regulator plate?-RESOLVED, Trying to solve reverse lights not hooked up Options

[HalfMoon]

In solving more problems for my 1973 v-8 converted 914, I need to hook up my back up lights (they were removed by the PO presumably during the conversion).
The switch is on the trans, but there's no wires to be found.
When I examine the wiring diagram (picture enclosed) for a 1973, I see the wires run to the switch (from the lights) onto the trans switch then to a thing called #90 "Regulator plate".
No idea what this is or where it's located and Haynes makes no mention of it. As a guess, is this part of the stock system on or near where the regulator would have been? From the "Regulator plate", wires then go to #35 stop lamp switch.
Where is the regulator plate located and where is/was the regulator itself located?
Thanks all :-)
Btw, still working on the wiper problem. Switch suspected.