The XD housing is 300% stronger in end of travel load testing.  The added strength is in the mil-spec alloy housing.
The cap is held securely in place with a hex lock and snap ring.

EXTREME DUTY lower screw in balljoint common on most dirt late models fits Rocket/Longhorn/Mastersbilt

Cross to Moog K727

1.5" per foot taper
3.82" stud length
5/8"-20 thread