pishta's post looks good. I got my info on the 8-pin from the megasquirt site (search "8-pin HEI" on google), which might be where he got the images.
Here is how simple the wiring is:
The 2-pin Metripak connector goes to the GM coil, using their factory cable. The thick red wire at the coil gets +12 V ignition. The white wire is tachometer output (so thick?). Connect the little spade terminals (P & N) to the Mopar distributor wires. Ground the module with a dedicated wire and put it on a heat sink, using thermal paste. Done.
Somebody cut your coil cable (why?). Good that they snipped the little white connector from the GM pickup. It latches to the module, but is not weather-sealed. A fancy heat sink isn't needed, a simple aluminum plate should work, judging from where GM put the module.
You can leave the 4-pin connector open until needed for computer spark control. Do get the connector and install to keep out dirt, isolating each wire w/ heat shrink. It is standard GM practice to remove it during testing. I understand it simply gives no spark advance when open, so your distributor then provides the advance as normal.
Note I didn't tell you the polarity of the distributor wiring. I haven't run my 8-pin on my 64 slant yet, so don't know. I understand it will spark way off the mark and a bit erratic if the polarity is reversed. I'll post back when I get there. Not even working on my 64 right now (84 M-B this week).
You don't need to worry about the 4-pin spark control wiring if you use Holley's Commander 950 ECU (as I will), since it has an (optional) adapter cable direct to the 8-pin. It is given by comparing the 7 and 8 pin modules pishta shows.
I would like to know the price of the rabidgator spark controller. I lucked out and got the Holley ECU (alone) for $120 on ebay. I will try spark control when I go EFI on the slant. The rabidgator would be great for those using a carburetor who don't want to fiddle with weights and vacuum advance, plus get a more custom spark curve control. I expect you can leave the weights and vacuum action and have the controller just add to those. That is my plan, so I can bypass it on the road, if needed, and run a regular spark without just a "limp home" fixed advance.
