Ok I need some help from the experts.

I have a Tremec from a 96 mustang Cobra R, Ford motorsport bellhousing and a hays diaphram 10.5 clutch with a pusher slave cyl. The clutch will release when I push in the pedal but when i try to put it in reverse it grinds and I have to shut off the car to get in reverse?

Does anyone have any ideas? All parts are new, The shifter is a Pro 5.0.
Thanks, Ray Hedden
