transmission hard shifting

I seriously need help. I am wondering if changing my transmission fluid in my 97 crown vic will make the hard shifting better or destroy my transmission I have heard do it and dont do it from people I have asked so far. The tranny has 140k on it and is not slipping, just shifting hard. If I should change it I am also wondering which fluid to use.

thanks,
Ryan

When is the transmission shifing hard? Full throttle or all the time? My 2003 Crown vic interceptor shifts so hard sometimes under full throttle that the whole car bangs and the serpentine belt chirps. I love hard shifts so it doesn't bother me. The rest of the time my tranny is super smooth.

it shifts hard all the time it also does the chirping thing when switching to third gear at full throttle so should I change my fluid?