Spicer drive shafts and components are as good as they get. Atlas transfer cases and any other 1310 series CV yoke. Measurements are taken center to center on the u-joint with the slip stub at the center of it's travel. Measure your vehicle on the ground in the running position to get correct length.
Replacing the clutches in your limited slip will restore the preload making your limited slip more aggressive like when it was new from the factory. Many units will have different clutch setups for an even more aggressive setup.