please help...if it's not one thing it's another....

You should not have points in a 75 Dart. It should be electronic ignition. Of course someone may have changed it.

Several things you can do. Find the ballast resistor up on the cowling or fender. Take your meter, turn the key to run, and see if one side of the ballast is "same as battery" the other side low. If they are both "same as battery," then the points are open.

Move your meter from the coil neg terminal to ground. IF the points are open that should show battery voltage with key on.

Bump the engine until the voltage at coil NEG terminal goes very low. This shows the points are closed.

Now put one probe of your meter on the battery stud on the starter relay, and the other probe on the coil POS terminal. You are hoping here, for a very low reading, less than .4V. If you read MORE than .3--.4v (4 tenths of one volt) you have a bad connection between there, the ignition switch, and the battery.

If this does not look too bad, clip your meter from the coil + terminal to ground, and crank the engine USING THE KEY. While the engine is cranking, take a reading. You should read AT LEAST 10.5 V and in no case less than 10V

If this is OK, you may have bad points or condenser, or a bad coil. A bad condenser will cause the car to not run. Make sure the points are acually opening and closing.

See if you have an igniton box like this on the firewall:

http://www.slantsix.org/articles/leanburn-article/ecu.jpg

if so, either you do NOT have points, or someone left the box on the car and converted to points distirbutor

Does the distributor have one or two wires for the low voltage connection? If it has a two wire plug, it's a breakerless distributor.