Whats killing my Duraspark?

The Duraspark has been working just fine for several years so I wasnt too concerned when it died 2 days ago.  I got a CBE7 replacement yesterday and it went less than 5 miles and quit working.   My first thought was ground, My battery cables are clean and tight, neg to engine  block, another ground strap to frame, My ignition module and distributor are grounded well, plus the module is bolted to the inner fender.    Any ideas?

I dont think it matters but this is a 1978 engine with 1969 DOVE 429 heads in a 1960 F100.

The aftermarket Duraspark modules are known for being unreliable to say the least. May want to check the coils primary and secondary resistance(could also be a wire that is broken internally, within the wire insulation), also make sure the coil is getting reduced voltage when the ignition is in the "ON" position(about 7.5 volts). Having 12v in this position will overheat the module and it will shut down until it cools off, the voltage at the coil when the ignition is in the "START" position should be 12v or battery voltage. Hope this helps.

ohm test the pickup coil, needs to be between 400,and 800, if its 801,or 399 it IS JUNK

I'll second what "aquartlow" said.
If getting a module, get a Motorcraft. The parts store brand ones rarely last long.

Thanks, guys. I really appreciate the  help.  The aftermarket module on the  truck  lasted 4 years.  I ordered a Motorcraft yesterday.  I hope I dont fry it.

  Pertronix coil instructions say  "No resistor required".   I have a resistor on my truck.  I get 12V on both sides of the resistor and I am getting 12 volts to the coil with the key in 'ON' position.

 1.8 primary resistance and the secondary resistance is about 9.5 on the ignition coil.  The pickup coil is 650.

a screwed up voltage regulator/alternator with either a bad diode or too much voltage will cook up durasparks as fast as you plug them in. bob

Thanks  Its a Delco 10SI one wire.  I thought its ok but will check it in the morning.I bet thats it.