No wire to ground on the TB IV ignition system. Just a simple adjustment for the TB IV system. The TB V system is the one that has a wire that has to be grounded.
mine really doesn't look like either system. I'm thinking now it might be the TB V system but with out the retard module.
I took on saltwater (cracked head) in June and just fired it up today. All appears to be ok with the lower end/block. I got the water out fairly quickly and circulated oil through the engine (by hand). Doesn't appear at this point anyways as if any damage was done to the rings/piston of that cylinder.
Figured I would take it to the river tomorrow and idle for awhile and set the timing/carb up.
It also says Thunderbolt IV ignition on the cover
Been awhile since I actually read what was on the cover, must be why the IV was stuck in the back of my mind
The SN doesn't help in determining TBIV or TBV, wish it did.
IF you don't have both the knock control module, and the ignition module mounted on the distributor, then you have a TB IV ignition.