I want to say that it engages both first and reverse, thereby locking the transmission until you release it. Someone correct me if I'm wrong.
http://store.summitracing.com/default.a ... 15&x=6&y=9 This one is about $400.

Don't bother checking with Jegs, the bastards will charge you about that much for shipping.

Summit racing is good, no problems and reasonable shipping.
(Yes, they sell a lot of parts to Germans as well.)