1969 Chevrolet Manta Ray Corvette Concept

The Manta Ray was actually the 1965 Mako Shark II with a few upgrades, 

so it featured many of the Mako II’s outward features, such as side exhaust 

and a lower-body (along the rocker panels) silver paint job. 

The front end had a pointed chin spoiler and the headlights used 2 banks of 3 quartz-hallogen lights. 

The covers for the side pipes eventually showed up as an option on the ’69 Corvette. 

Most dramatic was the all-new roof line. 
A gunslit vertical window replaced the louvered fastback rear window. 
Hard braking caused flaps on the rear deck to rise, reflecting light from upward 
facing stop-lamps (a feature first shown on the original Shark).
The Manta Ray also packed the new, lightweight, all-aluminum 
ZL-1 427ci engine which produced 430 horsepower. 
(carstyling.ru)

(Photos from corvettemaster.com, conceptcarz.com, netcarshow.net & carstyling.ru)

1965 Chevrolet Mako Shark II Corvette Concept

Mako Shark I was redesigned as the Mako Shark II in 1965. 

Debuted as a show car, its impossibly low nose and lift-off center roof section marked a
dramatic departure from the Sting Ray and pointed the way to the 1968-1982 C3 Corvette. 
Reclining the seats enabled the roofline to be three inches lower than the C2’s.
Chevrolet actually created two of them - only one of which was fully functional. 
The non-running show car sported some interesting, futuristic details, 
such as square section side pipes and a squared-off steering wheel. 
While the functioning version didn't have these features, it did have a retractable rear spoiler,
and a square section bumper that could be extended for added protection. 
The Mako Shark II was powered by a 427 Mark IV engine, which became available 
on production Corvette models. The paint scheme continued the Shark I tradition, 
with blue/gray on top and silver/white along the rocker panels. 
The original Mako Shark was then retroactively called the "Mako Shark I".
(wikipedia & carstyling.ru)

(Below L) 1961 Mako Shark I Concept           (Below R) 1965 Chevrolet Mako Shark II Concept

1970 - 72 C3 Corvette Coupe

1974 - 76 C3 Corvette Coupe

(Photos from oldiesfan67.canalblog.com)