1968 Shelby EXP500 Hardtop


1968 Shelby EXP500 Hardtop

1968 Shelby EXP500 Hardtop

In 1968, Shelby American tried out several prototype features on this experimental Mustang known as the Green Hornet. It was used for component testing and remains as one-of-a-kind GT500KR prototype. Unlike almost all other GT500s this car was built from an S-Code 1968 Hardtop (VIN 8F01S104288) that was one of Ford’s GT/CS prototypes.

Shelby took received the Hardtop at their new facility in Ionia, Michigan where “Walt Nelson, Fred Goodell, George Merwin and Ray Geddes transformed it into a true Shelby.”2. They fitted a 428 Cobra Jet engine which and it later debuted in April as the GT500KR. To handle the extra power, a Lincoln torque converter was fitted as was a F350 transmission. As such, the car became a testbed for the Cobra Jet engine and also other experimental components which Shelby were considering.

One of these was an experimental electric fuel injection system that Dave Long of Bendix was developing for the Ford/Mercury line. This was never put into production, but it’s an interesting footnote in Mustang.

An independent rear suspension was also tried in the EXP500. It used the rear leaf spring attachments for a basic half-shaft setup with lateral links. The 9-inch differential was retained.

Shelby American did all the usual upgrades to the car. The front suspension was upgraded and a set of ten-spoke wheels and F60-15 tires were fitted. “The body and interior were given the Shelby treatment. A complete ’68 nose with functional ram air hood, and a tail panel that accommodated the ’65 Thunderbird taillights were installed, and the GT/CS side scoops remained.”1

After the car was finished, it received “three coats of Gold Luster Green lacquer with gold metallic mica over the original topcoat. For additional brilliance each of three coats were hand-rubbed and the topcoat was treated to two coats of clear lacquer. Emblems and custom white/gold EXP500 stripes identified the car as a Shelby prototype.2

The power rating wasn’t published but the car did post a 0-60 time of 5.7 seconds and a top speed of 157 mph at the Ford Proving Grounds. Hemmings said “considering the 3.0:1 ratio in that 9-inch rear, a 3,500-pound test weight, and the tire technology available at that time, these are astounding numbers.”1 They also pointed out that Car and Driver posted a 6.5-second 0-60 mph time, an estimated 128 mph top speed for a stock GT500.

Later, the car was sold off of Ford’s Employee and Auction Resale Lot, but the special injection and rear suspension was long gone. Through several owners the only ’68 Shelby Hardtop was slightly modified, but not enough to elude Randy Darrow. In the 1980s he discovered his Shelby was a one-of experimental prototype and they approached Fred Goodell in 1988 to correct the car back to its 1968 specification. The restoration was finished in April of 1993 by Classic & Muscle Mustang Restorations of Midland, Michigan. The bolt-in rear suspension was fabricated while the experimental injection system was left off the car.

Later EXP500 joined the collection of Craig Jackson of Barret-Jackson fame. On the facts section of his website he lists the value as $1-2,000,000.

Sources & Further Reading.

1. Koch, Jeff. ‘Green Hornet’ Hemmings Muscle Machines. September 2006.
2. Jackson, Craig. exp500.com.

In Detail

type Professionally Tuned Car
built at Ionia, Michigan, USA
engine Cobra Jet V8
position Front, Longitudinal
aspiration Natural
block material Cast Itron
valvetrain Pushrod OHV
fuel feed Conelec Fuel Injection
displacement 7014 cc / 428 in³
bore 104.9 mm / 4.13 in
stroke 101.1 mm / 3.98 in
power 298.3 kw / 400 bhp
specific output 57.03 bhp per litre
bhp/weight 251.73 bhp per tonne
torque 569.4 nm / 420 ft lbs @ 3200 rpm
body / frame Unitary Steel Monocoque
driven wheels RWD
wheel type Aluminum 10-spoke
front tires F60-15 Goodyear Polyglas
rear tires F60-15 Goodyear Polyglas
front brakes Kelsey-Hayes Discs
rear brakes Kelsey-Hayes Discs
front wheels F 38.1 x 17.8 cm / 15 x 7 in
rear wheels R 38.1 x 17.8 cm / 15 x 7 in
steering Recirculating Ball w/Power Assist
f suspension Upper Wishbones w/Lower Control Arms, Coil Springs, Telescopic Shock Absorbers, Anti-Roll Bar
r suspension Indpendend w/ Coil Springs, Telescopic Shock Absorbers, Anti-Roll Bar
curb weight 1589 kg / 3500 lbs
wheelbase 2743.2 mm / 108 in
front track 1473.2 mm / 58 in
rear track 1473.2 mm / 58 in
length 4739.6 mm / 186.6 in
width 1800.9 mm / 70.9 in
height 1310.6 mm / 51.6 in
transmission F350 3-Speed Automatic
gear ratios 2.46:1, 1.46:1, 1.00:1
final drive 3.00:1
top speed ~252.61 kph / 157 mph
0 – 60 mph ~5.7 seconds
0 – 100 mph ~11.4 seconds
fuel capacity 64.34 litres or 17 gal.