There are other reasons for an engine to be misfiring over 3 or 4 thousand besides the firing system.
For instance, you could have a bad cap, bad wire, or something fouling the plugs.
You could have a vacuum leak in the induction...and on and on.
Everyone's experiences vary. I have NEVER heard of even one Duraspark MODULE failing. A "coil in a can", that's another subject.
I have had three MSD's fail.
I have had two Petronix 1's fail.
I have had one Petronix coil fail, BY LEAVING THE IGNITION ON with engine off.
Thier coils are a compromise design and under test do not deliver what Petronix claims that they do. You can overheat them.
You can always ask people for their opinions. Some think the flying monkeys took them. Some went for rides with "aliens" through the "Milkyway". Some think there is bamboo in the paper ballots in Arizona.
It helps if the opinions that you ask for are from people who know something about the subject and when an acorn falls, don't think the sky is falling.
These things just seem so obvious to me, that it largely goes unspoken...usually?
Personally I have found in doing this for over 40 years that the original Ford components are by far the most dependable. I won't tell you how old I am but it IS MORE than 30.
Aftermarket companies have rarely come up to that level of predictability and dependability.
I don't have the original CJ Pantera distributor part # but the '71 Boss 351 was stamped D1ZF-12127-DA and serviced as part number D1ZZ-121127D.
With the possible exception of the earliest '71 Panteras. the CJ's came with dual point/dual advance distributors and I would presume would have a D2ZF-12127-DA stamping.
The 351c CJ (Cobra Jet) appears in the '72 Model year. It is what is installed in the '72 and up Panteras and other Q code Fords. The distributor used is dual point and is functionally the same as the Boss 351 but with it's own unique ID number.
It uses a dual advance/retard vacuum advance with a 12 degree maximum vacuum advance. 20 degrees mechanical within the distributor. 12 to 16 degrees initial, depending on where you want it to idle and where the octane limit allows ping.
Originally they came with one medium and one heavy tension spring for the counter weights. That brought full mechanical advance in around 5,000 rpm. You can replace the heavy spring with another "medium" to bring total advance in around 3,000 rpm.
Beware using two light springs such as in the Moroso kit. The springs rapidly stretch and become dysfunctional.
ALL the Ford dual point distributors use the same points and CONDENSER as the earlier 289hp, 427hp, Boss 302, and 429cj Fords using the dual point distributors.
IF you are an "Archeologist" and must dig through the parts book, the '64-5 427 Transistorized ignition will show a different part number but it is really the same except for the additional lube wick.
The Pantera, Q code, dual point/dual advance design is different then the strictly mechanical advance distributors used in the 289hp and 427 Fords. It uses the same casting as the single point distributors but makes provisions for connecting the vacuum advance arm under the advance plate by using a different ball bearing advancing point plate and a different extended points cam to align with the higher mounted points.
Parts do not interchange with other distributors.
The dual points do have more initial tension so they do need more attention in my experience generally in the 15,000 to 20,000 mile range. Initially they are set at .021" clearance but some set them with a dwell meter. The dual points will give you the same dwell as the electronic Petronix will. Additional dwell with the original Ford yellow top coil is the reason for using dual points.
It helps if you use felt oiling pads and point lube. The felts were only supplied by Ford for the 427 Transistorized ignition distributors to reduce the frequency of adjustment periods.
I only see them serviced by Accel these days. They are way obsolete at Ford.
By far the simplest solution to a maintenance free system with the highest amount of star ratings and few if any bad marks are the Ford Duraspark systems.
Going with any other ignition system may (and likely) cause incompatibility issues with the Veglia tach.
Generic Duraspark systems seem to be just as good as the original Ford.
For additional ignition benefits, use the Ford Duraspark distributor with the Pantera-electronics ignition module.
IF you decide to go with the "Duraspark system" it will come with the large cap and an adapter for it. There is a small cap that fits it but is not a Ford application. It is for a 70 International Harvester with a 350 engine. It uses the same Ford rotor though as a single point Ford distributor does.
The Pantera ignition is a Ford design. It uses the Ford yellow top coil (9v) with a pink resistance wire. The tach is designed to work with that.
My Pantera is using the Duraspark II distributor with a small cap to clear the Weber carb system and male wire terminals. No problems with it in almost 35 years.
I'm not lecturing here at all. Certainly there are others here that will just plain disagree with me.
I Just share to help other "Pantera beginners" reduce the grief. The car is just a little unorthodox to most versed on US built cars and they sometimes make irrational assumptions on how to service it.
"Living in America is really neat. You don't have to run through the woods and scrape up your feet" - Randy Newman. 