1boxer1, you're on the right track. IMHO, plyometrics is the way to go to build strong powerful legs--especially for endurance. That is, of course, if you wish to equate speed and strength into POWER.

Of the many websites I've visited, Brian Mackenzie's is by far the most succinct on the subject.

For, specific, "leg plyometric" exercises, review the referenced link:
http://www.brianmac.demon.co.uk/legplymo.htm

Near the bottom of the referenced page are additional links for other body specific areas, i.e., arm plyometrics, high intensity plyometrics, etc.

Hope this information is supportive of your query, mate.

Best,
Herb