And it's pretty clear why many think LS engines are so special. They're powerful, durable, reliable, easy to service, and cheaper to tune, but none are more infamous than the LS6. The story of GM ...

Unrestored, highly original, and numbers-matching, this 1970 Chevrolet Chevelle SS 454 LS6 unexpectedly failed to set a new ...

but a retractable roof turns an LS6 into a super-rare rig. Again, precise production numbers are unavailable, but Chevelle experts agree that only 12 to 25 drop-tops got the 450-horsepower engine.

When buyers ticked the $503 box for the latter engine, they also got heavy-duty suspension, power front disc brakes, and SS wheels along with the monster motor. The 454 came in two specs, LS5 and LS6.