I've posted on this before... I prefer the "firmer and less-slop" press-in 914 hard plastic pieces over brass.
Why?
The action of the joint requires a true universal joint. The brass restricts motions to one plane..it doesn't "work" like a true universal. The hard plastic will be "better" than the slop unit used for 911's...yet will "give" a bit better than brass. OR...use a true universal like the Stomski unit and such....
The possible consequences of "forcing" a brass unit beyond it's movement limits is add'l trans wear...
Do a search...there is a long thread with pro's / con's of each method described.
- Wil
EDIT... look what Wevoid and Chuck Moreland have to say here------->
http://forums.pelicanparts.com/showthread.php?threadid=128478&highlight=shift+coupler
...not many are heeding this sound advice...