Can we convert the Shelby Cobra file to .stl?

You could import it into Rhino and convert it to an STL.
best
Vic

Did you put this question on the upload file for the uploader to read? It is up to them, not GrabCAD

Thanks, Aaron. I di put this question for the uploader to read.

FreeCAD can import STEP and export STL. I've had nothing but success so far.
And, as the name implies, its free. http://freecadweb.org

If you're looking at 3d printing, I'd also recommend cleaning up the stl with the free version of netfabb. http://www.netfabb.com

STL files can be read by the Catia V5 Reverse Engineering module. You can use the result "as is" (instant) or build the geometry with the RE tools (work content depends on the required result).