I know this is going to start a sh*** storm but if your car sees any street driving at all -- forget about the spool idea --- and also c-clip eliminators -- both are not street friendly --- go with an actual Eaton Detroit Locker as I mentioned above and you will be fine for both street and track---
actual Detroit Lockers have been around forever and are proven -- they did install them in 70's Drag pack optioned Mustangs// Cougars/ Torino etc.
I always run one in my street cars and have installed many more in various Fords and Mopars for fellows that wanted the best /strongest differential for street and track use.