Phantom Grip is an inexpensive LSD, which is spring-loaded LSD instead of the conventional clutch-pack LSD.
Overview
It installs into a regular open diff, not requiring the special:
Be sure to read these discussions of the Phantom Grip:
* sprung load locker = phantom grip
Limited Slip Vs Locking
LSD = limited-slip differential, NOT locking-differential. If it prevents straight-line slip but doesn't lock up around corners, then it is LSD. There are various types of LSD and most are spring-loaded. Ford diffs use a spring-loaded clutch-plate design (more complicated than the Phantom) and the biggest downside is that they wear out rather quickly.
Longevity
Depending on how you drive a phantom can last for a long time, to my memory mic had it in a rally car for 2 years then I had it in a road car for bout the same and at the end it started slipping but just needed to be re shimmed. supafatto