
It's a support plate that mounts & supports on the bell housing between the 4th and 5th gearsets.
It also acts as a better mount for the bearings, and a trust plate for 4th/5th gear.

I found it in a group buy over at Club Protege.
http://www.clubprotege.com/forum/showth ... -plate-mod
The group buy is over... but if this is all it takes to reinforce the tranny, $300 is well worth the price.