Sorry to hear about the seizer. I believe you have a 2v so any 4.6L 2v from 1998 to 2002 should bolt right in with no changes to the computer. However, some of the engine sensors were slightly changed, and you may have to rewire connectors to extend or make the correct connection. Be sure you get a wiring diagram for your car AND for the engine you are installing.
1998 was one year Ford starting making changes to all the cars. And some changes were just for 1998;some for the better (and were carried over to the next couple of years), and some for the worst (and they went back to pre-9

.
Now the bust everybody's bubble. The P71 was a HD package done to the Crown Victoria for severe usage, like police and cabs.
The suspension was given HEAVY DUTY parts for minor off-road excursions. Some of these parts are strictly for the P71, as it does have a harsher feel.
The engines were equipt for extended idling (larger fan, larger coolers, additional coolers, higher idle speed). These are the same engines used in the civilian models. Normally a 130amp alternator was used, but some were given the 200amp models due to the type of police package installed (more radios, lights, sirens).
The computer was programmed for higher idle speed, different shift points for the transmission, and higher top end. These can all be accomplished with a tune.
The rear end differential was lower than the civilian model (3.0

, usually a 3.27 open ratio. Some did come equipt with 3.27 locked or 3.55 locked. With a lower gear, the car felt like it had more power because you got into the power range QUICKER.
You may want to go to www.crownvic.net , PantherFreedom.net, OR CVPI.org for more info. The Crown Vics, Grand Marquis, and Town Cars are essentially the same vehicles, just a change in luxury levels.
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PROUD MEMBER of www.crownvic.net
It's just a SUPER-DUTY Mustang GT Sedan. 198K miles and still rolling HARD.
1997 Crown Victoria P71 SVT *** ex-US Marshall service (the CAR)
STOCK?? I bet it was modified.
13.26 @ 107.24 MPH 1/4 mi w/ me, tools, & full tank of 93 octane
I added CAI, NICHE 19 X 8.5 " wheels with 245/45ZR 19 rubbers, and completely rebuilt the front end with poly bushings, Kooks headers, 2 1/4inch exhaust, TCI 2200-2400 rpm Stall converter
.PLANS:: engine upgrade, 5.4L 2v stroker, rebuild interior in leather w/ buckets, thinking about turbos