Ok here is the problem with the spool on the street....
1. you can't make any HARD corners
2. you will break axle bearings
If you are serious about a spool....
You must make the widest turns possible, not more parallel parking, no parking in parking lots, no u turns......
Otherwise you break the outer race of the axle bearing....
I rebuild rears with guys and spools on the street and this is what happens when you make that 1st killer turn...very few listen, and i see them often with the same noise or complaint....
After a few axle bearing changes....you'll be past the cost of the best Selectable locker... or you'll have no clue and think you have no problem