Brad Bowling
August 6, 2007

Have you ever walked up to a restaurant 10 minutes after the posted closing time only to have a nice waitress take pity and unlock the door? Usually, she glances around to ensure you're alone, hustles you in, and you feel special all day.

In 1972, Ford Motor Company officially locked the door on its Boss Mustang program after three successful years and three distinctly different cars. The Boss 302 and Boss 429 were produced as '69-'70 models, but the '71-only Boss 351 was a happy medium between the 302's road racing prowess and the 429's dragstrip dominance.

Central to the '71 Boss identity was a 351 Cleveland V-8 designated with the code "R." The Boss engine was similar to that year's other high-performance 351, the Cobra Jet, in that they both had four-bolt main caps, 2.19-inch intake valves, 1.71-inch exhaust valves, forged-steel connecting rods, an Autolite 4300-D four-barrel carburetor with a spread-bore pattern, a dual-point distributor, and a cast-iron crankshaft. To produce more power than the CJ, the Boss engine used a different combustion chamber design-the "quench" shape-that closely shrouded the valves and increased the compression ratio substantially. Other power producers were solid solid lifters, adjustable valves, a mechanical camshaft, and forged aluminum pop-up pistons. With standard ram-air induction, the Boss put out an advertised 330 hp.

Available only with the SportsRoof body, the Boss 351 also included a blacked-out hood (silver was used when certain exterior colors were ordered), a 3.91:1 Traction-Lok rear axle; a four-speed transmission; Competition suspension; power front-disc brakes; and various cosmetic upgrades such as hood-lock pins, a front spoiler, a Mach 1 grille, and a chrome front bumper. Standard Boss 351 tires were Goodyear F60x15s with white raised lettering on 15x7-inch stamped steel wheels wearing hubcaps. Chrome Magnum 500s were optional.

At $4,124-about $150 more than the previous year's Boss 429-the 351 was Ford's most expensive non-Shelby Mustang to date, and one of its quickest. Despite a shipping weight approaching 3,200 pounds, the fastback could fly through the quarter-mile in 14.1 seconds at 100.6 miles per hour according to Car and Driver, and 0-to-60 times in the sub-6.0 second range were reported.

Had it not been for a slowing American economy, rising insurance rates for performance cars, and increased government regulations concerning safety and emissions, Ford would gladly have continued the Boss 351 for several more years. Unfortunately, the company only found 1,806 buyers for the '71 Boss-compared to nearly 8,800 Boss 302s and 429s-and realized the market for premium-priced, high-performance vehicles had come to an end. Ford announced there would be no '72 Boss, leaving a crowd of hungry performance enthusiasts with noses pressed against the glass, wishing they had arrived just a few minutes earlier.

Fortunately, a few knowledgeable Ford sales people explained that the '72 Mustang order form could be used to create a Boss in all but name. Checking the box for the R-code engine-what Ford called the 351-4V High Output-bought a host of mandatory carryover equipment from the Boss, including the four-speed, a Hurst shifter, and a 3.91:1 rear axle at an additional cost of $812.