The Longfield™ Gun Drilled 30-Spline Birfields are made out of 100% chromoly and are precision polished to remove any imperfections that may cause stress risers. The internals of the birfield are also made from 4340 chromoly and are dual heat treated for superior strength. The birfield has a M8 grease zerk at the end of the stub shaft and is gun drilled through the center of the birfield to allow for grease to pass through the zerk fitting and into the internals. This will save you precious time by eliminating the need to disassemble your axle just to service your birfields. (more…)