Not necessarily the most valuable or coveted by our group here but don't forget some of the earliest most significant performance cars in Chevrolet history were actually F

RDS!.
After unloading his interests in Chevrolet to GM founder Billy Durant, Louis Chevrolet a his brothers got back to their real love...racing!.
The Chevy Bros Frontenac Motors Co. produced the very successful 'Fronty' Ford racers also making their modified heads, parts and cars available to other racers..
Sound like anyone else you know of?

.
Here's a bit of an online blurb on the subject..
http://www.modelt.ca/speed.html
~ Pete