My 97 didn't have the new pistons, it still had the aluminum ones with the orings. I didn't have a broken upper spring, but I replaced it with the one listed for mild settings as well.
I don't know if the cover is needed or not, it was supposedly redesigned, I THINK it is a different depth to affect the spring height, but I don't know, I just replaced it with the other one, I don't know if is listed to just have a new one that seals or if the sealing surface is different or now ::shrug::
97 Mark VIII LSC/Silver/Gray leather
97 Cougar 4.6 Sport/White Opalescent Tricoat Metallic /Gray leather down but not out?
89 Cougar LS 3.8/Oxford White/Gray velour/HG need replaced AGAIN
00 Grand Marquis LS/Vibrant White/Gray velour
63 Falcon 302/black and rust/shed isn't moving
82 F-150/Oxford White/dumb VV carb doesn't pass emissions