1970 Ralley Dash Voltage regulator?

I looked around briefly on Google for some answers and only found some limited answers. I just got done redoing my 1970 ralley dash for my dart. I know the gauges only run off a 5v feed (otherwise they would fry). When I pulled my dash none of the lights worked or anything. Only gauge that worked was my tach. I didn't see any voltage regulator on it though...I read that the fuel gauge has an internal regulator that takes 12v in and then has a 5v out terminal. Is this correct or am I just missing the regulator? If this is correct which terminals are which? Thanks for any help