All it is, is a valve with the lands ground a little differently to seal the fluid in the VB, and lets the fluid circulate in park.
It's not that the pump doesn't pump in park, it's that the valve blocks the circulation in park.
The kit valve makes it where you can chk the fluid in park after that, because the fluid is circulating.
Chk out this link and about 1/3 of the way down the page.
http://www.cuda-challenger.com/cc/index.php?topic=20391.0
