I like that it came with new bearings. This thing is super solid, indestructible. I have both front and rear metal difs and my buddy has the same exact 1:16 brushed motor sonic and mine is clearly faster.
Metal Differential - Part Number BL-ZJ06
It work great but I didn't get other upgraded parts. I will be ordering them soon
Holds up great a must for brushless upgrade. Plastic gear will not last long with brushless motor upgrade.