You don't need to replace the solenoid if it is working fine. You do need to pay close attention to the solenoid gaskets, and make sure they are put on the correct way, or else the tranny won't shift properly.
Pete...
2004 Mercury Marauder 300A
Black Clearcoat/Dark Charcoal LEATHER
DOB 10/31/2003
DOP 1/2/2004
www.mercurymarauder.net