Coil selection
Your stock coil might work OK for awhile, but really isn't a good choice. At the very least, replace it with a coil meant for use with electronic ignition. Such a coil would be a Standard-BlueStreak #UC16 or NAPA Echlin #IC27. It's best, though, to use a coil intended for use with a high energy ignition system. If you'd like to mount the module off by itself somewhere, then a good coil option is the stock external-mount E-core coil used with Ford and Mazda high-power electronic ignition systsems. The premium version is Standard BlueStreak #FD-478X:
You can save eight whole dollars by specifying the ordinary FD-478 (or NAPA Echlin IC-24) instead of the premium FD-478X, or you can save a whackload of cash by specifying the cheap Chinese FD-478T or NAPA Echlin IC-24SB (not recommended). If you're going yard-hopping, you'll find this coil in '82-'97 Ford cars and trucks, '84-'94 Lincolns, '82-'95 Mercury and '85-'89 Merkur models, as well as '94-'97 Mazdas. You can grab the connectors and a few inches of primary wire, as well, or if you'd like to have a new connector with wire, use Standard #S-539:
Another workable coil is the GM HEI coil used on '75-'84 GM cars mostly with 4-cylinder engines, Standard #DR-35 (no premium "X" version available) or NAPA Echlin DR-35.
Combination coil/module/heatsink/bracket
A tidy option is to use the combination HEI coil/module/mounting bracket originally found in just about all gasoline-fired GM pickups and RWD SUVs from '96 to at least '00. It includes a nice sturdy mounting bracket, heat sink for the module, E-core ignition coil…all in one:
Wherever you are, you can probably pull these out of wrecking yards all day long for very little money, and you can just grab the watertight connectors for the coil while you're there. This way you take advantage of GM's own work. The newer style module included with this setup (and shown in the photos above) won't work with the Mopar distributor; it's looking for a 0-5 volt square wave, and that's not the kind of signal the Mopar distributor puts out. You can use the early type (4-pin) module—part numbers specified above in the discussion of module selection—on the newer heat sink bracket with minor mods to the heat sink. Then just bolt the combination module/coil/heat sink unit to the inner fender:
If you use this combination coil/module assembly, the original coil has three terminal pins:
A is the coil's primary (+) terminal; gets ignition-on 12v and is connected to module pin "A".
B is a tachometer signal output. Not used if you don't have a tach.
C is the coil's primary (-) terminal, goes to module pin "D"
The only other "gotchya" is that many of these E-core coils have a male (spark plug type) output terminal rather than the female type on our original coils, so you'd need to get an appropriate coil-to-distributor-cap cable such as NAPA Belden #701050, which is a Ford item, or the equivalent from Magnecor or your favoured spark plug wire supplier.
