The 1970 Mercury Cyclone is one of my favorite muscle cars.
One of my first and favorite cars was a 1970 Mercury Montego,
the poor mans version of the cylone. Although they are almost identical 
in appearence, the cyclone had a bulls-eye style grill with an extra 
running light/turnsignal on either side of the grill and an additional
tail light on each side. Click the image below for a larger view.

The difference can be seen in the pictures at
the bottom of the page. The top pictures are of Cyclones and the 
bottom 4 are of a Montego MX. The Montego MX also has the additional
tail light that the standard Montego did not have.
My Montego had a 302 to which I added a 4bbl carb and dual exhaust,
headers are damn near impossible to add to the montego due to the 
shift linkage.
While it wasn't the fastest car in the world, my montego ran like a top.
It never gave me a bit of trouble.
I did own a 1969 cyclone with a 351 windsor at one time, but I still like
the style of the 70's better. The feature I like most about the cyclone
is the optional instrument cluster located in the passenger side dash
slanted toward the driver (very cool looking).