Okay, I'll bite, but for the last time... I'm a glutton for punishment.
It's an MSD... It's not an MSD... It's a Summit MSD knockoff... It's an MSD again... It's a Summit Mallory knockoff...
PLEASE PLEASE PLEASE figure out what you have, and post accurate information. Model numbers, part numbers. Ignition box, coil, distributor. MSD, Summit, Pertronix make many different styles and models of ignitions and coils and they're NOT ALL THE SAME. "Wired according to MSD's instructions" is meaningless if it's not an MSD... And saying "it ran great until it didn't" is no help at all- is there spark, did you actually test for spark? What type coil are you attempting to use? They aren't all interchangeable.
And please quit saying "it's working fine". It isn't. That's why you're here. And saying "they must be good otherwise they wouldn't keep selling them" is a cop out. The market is full of garbage that people keep buying. Not saying your system is, but I don't know what system you have.
So, if you want "a little less option (sic) and maybe some constructive help", start by giving us actual information, and stop assuming it can't be this or that without actually testing the component- it is, after all, not working.