These are machined from billet instead of cast like the originals. However, it appears that they are machined such that the ring gear is pushed far too strongly into the pinion gear, and the resulting assembly is gritty/notchy. This is something we and our customers have discovered, and have reported to LC Racing.
We recommend using the standard L6258 and L6271, our Class 12.9 differential screws , and our aluminum gearboxes for the ultimate in durability. We have never damaged a gear since with that setup.
California Residents
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.