Regulator Ground wire
 

My car is missing the regulator ground wire - does anyone have a picture or diagram that shows where it goes - thanks.

What do you have for a car?

You can't go wrong if you connect the reg ground to the dynamo, be it an alt or gen.

Regulator Wire
 

I have a '68 FB 400 with automatic and a/c. The previous owner did a hack job on the wiring - lots of splices and electrical tape. The reson Ilm asking is my GEN light stays on with the key off.

Ground the reg. If the lite still stays on change the reg then test alt, but before anything check the rest of the alt and reg wiring to be sure it is correct.

when the motor is off and alt not turning the idiot light should get no power. It should be connected to a power source that is hot only when the key is in the RUN position. when the motor starts and the alt starts charging the alt sends 12v to the idiot light and it cancels the other side and light goes out.
So... you must have the idiot light wire hooked to a constant 12v source such as the cigar lighter wire or horn wire or brake light power source.