It isn't often I get the chance to photograph a Corvette twice, but this isn't just any Corvette. Seventeen years ago, I shot this LeMans Blue '69 roadster for another publication, and at that time the question arose if the car was a real ZL1 Corvette. The owner made no claims that it was, but much of the car's configuration was right enough to be either an L88 or maybe-just maybe-a 585hp ZL1.

For those unacquainted, the saga of the ZL1 Corvette reads like a Tom Clancy novel. The ZL1 was a midyear engine release for the '69 Corvette and was slated to replace the legendary L88. It boasted a beefier, all-aluminum block; stouter connecting rods; and open-chamber heads that flowed better than the L88's. The ZL1 was also lighter, weighing about the same as the L46 small-block. And it was expensive. The ZL1 option cost $4,718.35, while a '69 Corvette coupe cost $4,781.00.

The ZL1 option also required a handful of mandatory options-the F41 Special Front and Rear Suspension ($36.90), G81 Positraction rear axle ($46.35), J56 Special Heavy Duty Brakes ($384.45), and K66 Transistorized Ignition ($81.10)-raising the total price of the ZL1 package to $5,267.15. And that was on top of the Corvette's base sticker, so if no other options were ordered, the tab for a ZL1 Vette was a hefty $10,048.15. Radio and air conditioning were not available with the ZL1 engine.

With that nosebleed price tag, not many ZL1s were produced. Records from the Tonawanda engine plant revealed 94 ZL1 engines with Corvette prefixes were built-80 coded for use with manual transmissions and 14 for use with automatics. It's acknowledged among Corvette historians that the majority of these engines were sold to racers, but a few went over dealers' parts counters to private parties. Although two ZL1s were sold to the public, only one has provenance and pedigree (read: documentation). The other has never been fully documented.

Before these engineering cars were retired, both Popular Hot Rodding and Road & Track magazines got their editorial mitts on one. PHR was able to run an 11.0 at 129.45 mph in the quarter-mile. R&T took the 2,945-pound ZL1 and recorded 0-60-mph acceleration in 4.0 seconds, while the quarter-mile was over in a short 12.1 at 116 mph. These were mind-boggling speeds and took the standard Corvette chassis and brake systems beyond their design limits. Unfortunately, all this Saturn-rocket stuff was quickly over. Duntov and his staff knew the ZL1 would have to be cut in 1970 to meet stringent new EPA guidelines. But it was glorious while it was around.

There are also a handful of ZL1-equipped '69 Corvettes in the hands of the Chevrolet Engineering Department, including one once piloted by Chief Engineer Zora Arkus-Duntov. The story goes that these cars were used as performance testbeds for driveline and suspension upgrades. What happened to them remains a mystery, although it's believed the engines were yanked, the production big-blocks reinstalled, and the cars put up for sale. And where did the ZL1 engines go?

Our feature Corvette is now in the hands of Rick Treworgy, of Punta Gorda, Florida. Rick's owned the car since 2001, and he's researched the car's provenance. He believes it started life as a big-block, perhaps an L88, especially since it was minus the radio straight from the factory. Some of the numbers on the Corvette and the ZL1 look tantalizingly close, but no cigar.

The owner of record in the mid-'70s purchased the '69 in baskets, and the Holy Grail of Corvette restorers-the tank sticker-was long gone. The tank sticker is a copy of the build manifest and contains information about the car, including the options and accessories as equipped from St. Louis. With it, you have full documentation. Without it, well, you have supposition. Like the yellow ZL1 that belongs to Roger Judski, Rick's car has the black stripe that runs the width of the headlamp panel and up along the rise of the front fenders. It's been there since the car was restored in the '70s. Also still fitted on the roadster is the RPO C07 Auxiliary Hardtop.

Rick isn't hung up on the '69 roadster's mysterious past and how it ended up with the most exotic and most powerful production engine Chevrolet ever sold to the public. All he knows is that it's one hell of a car to drive. The restoration done years ago has held up well, with the only visible change being the replacement of the Western turbine wheels for a correct set of Rally road wheels. One thing that hasn't changed is the curiosity that surrounds this car. Did it start life as an L88? As I wrote in 1989, only Chevrolet knows for sure.