This Allstar Performance spool is a fullsize, 40-spline steel spool built for Ford 9in rear end housings with a 3.250in case. A spool replaces the differential carrier's spider gears and side gears with a solid unit, locking both axles together so they spin as one. This eliminates differential action entirely, sending equal power to both rear wheels for maximum traction in drag racing and oval track applications. The 40-spline design is engineered for high-torque applications where axle spline count needs to match the spool bore precisely.
Compatibility: Fits Ford 9in fullsize third-member housings with a 3.250in case and requires matching 40-spline axles. Not interchangeable with the mini spool family or the 26/28/31/35-spline fullsize spools listed separately.
FAQ
What does this spool do?
It locks both rear axles together so they rotate at the same speed, removing differential action for maximum power transfer to both tires.
What spline count does this spool use?
40 spline, and it requires matching 40-spline axles to install correctly.
What case size does this spool fit?
It is built for Ford 9in fullsize housings with a 3.250in case.
Is this a mini spool or a fullsize spool?
This is a fullsize spool that replaces the entire differential carrier, not a mini spool.
What material is this spool made from?
Steel.
