Ignition Prinary Ignition Resistance

Really Confused here. Does the 74 with 350 and points use a resistance wire to the positive side of the coil or should there be a ballasast resistor. All the Coil replacements I have looked at indicate use with external resistor, includining the AC Delco Coil U505 specified. I measured the voltage at the postive side of the coil and it is 12 volts so I assuming there is not resistance wire or ballast resister. Maybe it was hacked out from previous owners. If there is no resistance would the points burn out? 

The 74 wire diagram shows a resitance wire in line with the Coil, and has the starter circuit that bypasses it during start.

The resistor is actually the wire itself. This wire should be cloth-wrapped, and come out of the harness right by the wiper motor on the driver side. No ballast resistor, just the wire itself. Your's may have been replaced somewhere down the road...who knows?
You should only have a full 12v at the coil while cranking, and that voltage does indeed come from the starter.
And yes, a full 12v all the time at the coil will eventually "burn" the points, as well as stress the coil. If your car doesn't have the resistor type wire, you can install an external resistor, and be safe...

Thanks for the info...answers a lot of questions. Just one final thought here, I replaced the engine harness this past winter, does the resistance wire originate at the ignition switch or at the bulkhead connector. Also, what type of external ballast esistor would be in order, 1.5 or 3.0 ohm?

one way you might be able to tell, is with a test light at the + side of the coil with key on, then have some one crank the engine over the test light should get brighter. not sure but maybe I should try this on my old chevy truck

By definition, an in-line resistor only lowers voltage when currant is flowing.  If you measure the voltage without the engine off, you will get 12 volts, but if you measure it with the engine running, it should drop to six to eight volts.

Larry