People, people, people...
The police package for the Caprice Classic had the LS1 in it (Old-RWD Caprice), 5.7 (350) Corvette engine in it. Now they use the 3.8 V-6 (NON-Supercharged) and FWD (Looked down on very much) Impala. Usually they use these vehicles for inner city patrols and not for chases. (Very heavy car. 0-60 in about 9 seconds)
The police package for the Crown Vic has the 4.6 - just slightly modified, The older ones used 5.0 High output - and even older ones used a 5.8 2bbl carb (Old-school). Pretty plain and simple. Cop's like the RWD and the Crown Vic has been around since the dawn of the Earth - and Ford prices them just right so they stick with them. They even have good power (even for the heavy Crown Vic body)
Now Chrysler (even though that I am a HUGE Mopar fan) has been a joke on their part for cop-car packages and that is why you don't see many cars for them. But hopefully that'll change with the magnum...
Hope this helps out a little bit!!
Also - about the blowing engines part - I have never seen/heard of that. Cops blow the suspension apart due to how hard they are on it but the 350's/LS1's are a VERY STRONG MOTOR. (And they all have to have goveners on the RPM side. If you don't you can revv the engine in neutral until it blows (under 20 seconds) - but don't get this confused with a Speed govner. You can go as fast as the engine can get you until the friction of the wind stops you!

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