msd 6a fault???
That applied to every electronic ignition out there. There are plenty of chebby guys that carry a spare HEI module & the tools to change it in the glovebox. I have watched a friend replace 2 of those in the past couple of years in his daily driver.
I have had ford OEM TFI units die, with no warning - just a failure to start. Usually at about 60k miles. The older duraspark was the same way.
Mopar orange box/chrome box/blue box etc. mag triggered ignitions die as well.
Since the MSD 6 series has been in production for decades (there is a 40th anniversary model) and it has been fitted to all makes & models - there is every chance that there are more of them made / in service than the mopar box. There are a lot of them out there. Some will fail. The percentage is very low.
All electronic ignitions can fail. I had a Pertronix that almost caused me to replace a damper - the timing would drift over 30 degrees while you watched the timing light. Glad to see the OP got it sorted out.
If you want an ignition that fails slowly - stay with Kettering's points. Of course you have to maintain them, and they can't give you that powerful spark CDI can. But they are dependably mediocre.
B.