TrimDrip

if it is an automatic, you will go through three transmissions before the motor gives out.

My dad's v-6 motor is just short of a 1/2 million miles. I would take a 5.0 over it as far as reliability any day.

Riceinator

They will last a LONG time if maintained. Just don't buy someone elses problems, meaning it hasnt been all chopped and hacked up. I would look for a clean, stock(or close to it) stang and go from their IF the price is right.