No spark when cranking
First, this DID all work on thousands of cars Second, "sometime" later, Ma redesigned the ECU and went to a 4 wire design, which eliminated the need for the dual ballast. YOU CAN NOT ID a 4 wire vice 5 wire by looking. Many "4 wire" ECUs have 5 physical pins, so you must "ohm" the plug and see if the pin shows continuity anywhere
So far as GM, that is EXACTLY what I did. Many use the later GM modules, which allow electronic retard control. I simply used a 4 pin. I didn't even use a heat sink. I simply screwed it to a flat area on the firewall Notice the Mopar distributor connector. This is important The HEI has a small projection for indexing. You can either break it off to mount flat, or drill a matching clearance hole on your heat sink
The main reason I went HEI is because of modern Chineseation of replacement parts. In terms of "down at the present day store" I know of no brand name, including NAPA / Echlin / Blue Streak, or anybody else, that truly makes quality Mopar boxes. Since there are scads more GM HEI around, they are cheaper and easier to get, if not better.
Also, notice you no longer need a ballast. EVEN IF you use the factory coil, you get a bit more spark out of it. The final icing is that if you leave the key in "run" as in when testing, the GM does not draw coil current when at rest
Also, I rattled together this little box to fire up used engines, and then realized it makes a perfect "throw in the trunk" emergency ignition 
First, this DID all work on thousands of cars Second, "sometime" later, Ma redesigned the ECU and went to a 4 wire design, which eliminated the need for the dual ballast. YOU CAN NOT ID a 4 wire vice 5 wire by looking. Many "4 wire" ECUs have 5 physical pins, so you must "ohm" the plug and see if the pin shows continuity anywhere
So far as GM, that is EXACTLY what I did. Many use the later GM modules, which allow electronic retard control. I simply used a 4 pin. I didn't even use a heat sink. I simply screwed it to a flat area on the firewall Notice the Mopar distributor connector. This is important The HEI has a small projection for indexing. You can either break it off to mount flat, or drill a matching clearance hole on your heat sink
The main reason I went HEI is because of modern Chineseation of replacement parts. In terms of "down at the present day store" I know of no brand name, including NAPA / Echlin / Blue Streak, or anybody else, that truly makes quality Mopar boxes. Since there are scads more GM HEI around, they are cheaper and easier to get, if not better.
Also, notice you no longer need a ballast. EVEN IF you use the factory coil, you get a bit more spark out of it. The final icing is that if you leave the key in "run" as in when testing, the GM does not draw coil current when at rest