Andrew Hack was simply looking for a Mustang driver. With his '71 Boss 351 disassembled for restoration, he was perusing eBay when he spotted a Grabber Yellow '71 Mustang fastback with Mach 1 markings. "With Boss 351 values rising, I knew I wouldn't want to drive mine once it was done," he says. "So I thought this fastback, which resembled a Boss 351, would be a fun driver."
Andrew also noted the car's VIN-1F02H100053-and realized it was an early production car. "I was surprised that only a few people were bidding on it. So against my better judgment, I ended up buying it without even seeing it."
It took two weeks for the car to be delivered from San Francisco to Andrew's home in Wisconsin. Once in the driveway, Andrew noticed the car's unusual equipment and trim. It had a Top-Loader four-speed and a 9-inch rearend with a nodular case and staggered shocks, which seemed strange for a 351 two-barrel car. It wasn't a Mach 1, yet it had Mach 1 stripes and urethane front bumper. And two-barrel cars didn't typically have dual exhausts. Although the car showed paint chips and a few spots of rust, Andrew felt it was too original-looking to be a previous owner's made-up car.
Andrew's Mustang has two data stickers-the top one with 1F02H100053... | 
...and another one underneath with a Boss 302 VIN, 1F02G100053. | 
This copy of a Ford Communications memo, obtained as part of the paperwork from Marti Autoworks, provides instructions to change the car's VIN from 1F02G100053, with the Boss 302 engine code, to 1F02H100053, for a 351 2-barrel engine. |
The answer came from Kevin Marti's Ford production database. In this case, Kevin wanted to deliver the news himself. "He wanted to make sure I knew that I owned an important piece of Ford automotive history," Andrew says. "He told me that my car had been a prototype for the '71 Boss 302 program that was canceled."
For years, Mustang enthusiasts have wondered whether or not Ford produced a '71 Boss 302, prototype or otherwise, before offering only the Boss 351 when Ford pulled the plug on its Trans-Am racing activities, effectively eliminating the need for the special smaller-displacement Boss engine. Ford Master Parts catalogs from the early '70s list '71 Boss 302 parts, including body decals (same as the Boss 351 but with 302 instead), air cleaners (ram air and non-ram air), and exhaust system. Motor Trend ran a photo of a '71 Boss 302 in its new-car issue in the summer of 1970. Recently, Mustang Monthly's Jim Smart located the Motor Trend photography in the Petersen Publishing library, which included a blurry shot of a Boss 302 engine in the '71 press car. We've even heard firsthand accounts of '71 Boss 302 sightings in the Detroit area in 1970. But no one had ever documented a real '71 Boss 302.
Until Kevin Marti dug up the paperwork.
Andrew Hack was simply looking for a fun Mustang driver. He ended up with a historically significant '71 fastback. | 
The car is still equipped with the 351C, although the second owner replaced the original two-barrel induction with an aluminum four-barrel intake and carb, along with headers. |  |
"He said he'd never seen anything like it," Andrew says. "The paperwork included six different invoices and a Ford Communications memo. The VIN had been revised. Even its tab on the instrument panel had been replaced by Ford."
Andrew was understandably excited. He began looking for clues and first noticed three holes in the passenger-side inner fender that matched the mounting pattern and location for a rev limiter. Then he found the smoking gun.
Noting that the data sticker on the driver-side door appeared thicker than normal, Andrew used a hair dryer to loosen the glue so he could lift it up and see if something else was underneath. He found the bottom half of another sticker-with VIN 1F02G100053, the G denoting a Boss 302 engine. "It was as though someone started scraping off the original sticker from the top, then gave up and slapped the new sticker over the original," Andrew says.