I Purchased boat a couple years back and have taken too long to restore it. Way too long... But, all is almost complete. Former owner indicated MC V8s had Thunderbolt V ignition systems with knock sensors. While motors were on stands, I noticed that "350 Mag Stern Drive" labels were on both distributor modules, including knock sensors. However, my manual indicates that these modules are for EFIs. My motors both have 4 barrel carbs. During sea trial, these worked great. I suspect former owner mixed and match available parts which would work OK, or should I have an ignition module specifically labeled "Thunderbolt V?" Not familiar with this specific module...