Replace the pump and the pressure valve is under the front pump gasket. It will be sticking up a bit from the case. Make sure all you seals and seal rings are on the pump too.

 

Well removed tranny and purchased new bypass valve and pump. went to install new pump (came as two pieces) and noticed the pump I received had a 12 tooth internal gear and the old pump had 24. I have to wait till Monday to return it so I was wondering if I can safely use the 12 tooth pump or do I need to return it?