I have a 31 spline Detroit Locker in my 59s 9", unfortunately, there are no good clutch type limited slips available for a 9".As the rear pinion support bearing takes up too much room, so unlike most other rearends, a 9" Traction Lok only has a clutch pack on 1 side, and even so, that side has fewer clutch plates than the clutch style limited slips most other rear ends utilize. Plus, to squeeze those few clutches in the 1 side of the carrier, Ford had to carve away a lot of material, so cracked side covers have also been a major concern with Traction Loks. They are borderline OK on a street only car, but a poor choice for street strip cars, especially with a stick trans and slicks. I have not tried a Tru Trac, but my understanding is those small gears inside are not very durable in high shock load situations, like a stick car on slicks. So it seems like for a 9", the only decent choices for a street strip stick car that gets launched hard, is a Detroit Locker, and a spool is the best choice for a drag only car. Yes, the Detroit Locker has some quirks, like the occasional snapping or clunking , and will tend to pull to one side if the unit is not fully engaged, or the tire diameters don`t match. But if want something strong, that will 100% lock up both tires every time, the Detroit Locker is it.
