I have used the MSD capacitive discharge (model 6A p/n 6200) for 15 years now and maybe 60,000 miles. The unit is intended to be triggered by a hall-effect or whatever inside the distributor of a modern car. However, it is perfectly happy being triggered by a set of points and it has a tachometer output. I left the condenser in the distributor but disconnected with the wire tucked out of the way. I also have a coil-to-distributor wire tucked away, just in case. I have yet to use them except for troubleshooting which had nothing to do with the MSD. The ballast resistor is still there but unused.
There are two problems with this, however; one is that when the truck sits for months over the winter, enough oxide builds up on the points that they don't make contact, so I keep a point file in the glove box. You also have to clean the points once in a while as there is not enough current to keep them clean.
The other problem is that when you don't have to change the points for years, you forget to lube the rubbing block and it wears down, the points close up and the timing retards. Then the exhaust manifolds overheat and burn the gaskets out of the exhaust pipe flanges and you break the studs because you didn't have alloy nuts last time you had it apart.
I had the stock coil for years but swapped it out fro the MSD coil when looking for an ignition problem that turned out to be spark plug wires. The higher voltage of the CD ignition takes a toll on spark plug wires. BTW if you use one of these, DO NOT grab ahold of a spark plug wire for any reason with the engine running. The voltage and current level produced by these units can be lethal. Also AM radio reception is terrible but that may be the radio's fault.
