1973 Ford F100. Dash lights quite dim. Turn signals V-E-R-Y slow. Haven't found the bad yet. Ideas?

 

Signals I would think to look at the flasher unit. Dim lamps I would pull a lamp and see what wattage your using. If I recall right you can get 2 different wattage lamps. be warned though if you don't know that the housing that the lamps anchor into can get very brittle and break from the heat of higher wattage/temp lamps

Or I could be way off base.

 

May seem kinda basic but make sure the headlight switch is turned all the way clockwise. This controls how bright the dash lights are.

 

Slow flashing combined with dim lights suggests low voltage(at least to cab). Check ground condition from battery to block and block to firewall.

 

x2 on ground. Also check for high resistance in the ciruit, easiest way is one lead at the fuse block and the other lead at the ground