1971 Mustang Boss 351 at Mecum’s 2019 Portland Auction

It can be said that the 1971-1973 Mustangs get the least amount of love among the classic Mustangs fans, second only to the 1974-1978 Mustang II. For a long time, I felt the same way, thinking they looked bloated compared to the 1965 to 1970 Mustangs. But measurement for measurement, they grew only an inch or two in each dimension (the same holds true with its corporate cousin, the 1971 to 1973 Mercury Cougar).

A lot of the so-called bloat is visual, especially on the SportsRoof model, which comes from its nearly flat back window. The design, courtesy of legendary stylist Larry Shinoda (who was brought to Ford by Bunkie Knudsen from General Motors), was at the time contemporary and stands in stark contrast to its more graceful, almost Euro-inspired Camaro and Mopar E-Body competitors. It's a quintessentially American design.

And displacing just 351 cubic inches from its Cleveland small-block V-8, it had the tendency to fly a bit under the radar of the insurance industry who, at the time, was pummeling owners of virtually every high-performance car on the market, especially those displacing more than 400 ci.

As Motor Trend Classic's then-editor Matt Stone reported in his Winter 2010 story, "Born in the USA, The Boss Squad," "The Boss 351 was a one-year-only model that followed the tried and true treatment of the 1969 Boss 302, with black trim, strong graphics, and a front spoiler and (optional) rear wing. Externally, from the performance perspective, the new hood employed functional cold air scoops that mated to a special air cleaner housing feeding the engine compartment."

Stone continued, "The Boss 351 engine received treated and tested rods and crankshaft, plus adjustable mechanical lifters, screw-in rocker studs, and hardened pushrod guide plates. On top of the engine, fed by the cold air scoops, the engine featured an aluminum dual-plane intake manifold and a 750cfm Autolite carb. Downstream of the heads were high-velocity, cast-iron exhaust headers, and a free-flowing dual exhaust system." In many ways, the 351 Cleveland V-8 provided almost all of the punch of the race-oriented, high-revving Boss 302 engine, but was more suited for street duty. And compared to the 428 big-block cars, then in their final year of production, it was the best-balanced 1971-1973 Mustang overall. Quite under-appreciated by those who look past its small-block charms.

This Grabber Yellow Boss 351 is equipped about as expected for the time with a four-speed manual transmission, 3.91 Trak-Loc differential, power front disc brakes, manual steering, Sport Deck rear seat, and Magnum 500 chrome wheels. Absent air conditioning, this Boss 351 a windows-down tourer.

Interesting, from Stone's 2010 Motor Trend Classic feature, is the quote from the original January 1971 road test from Motor Trend's Chuck Koch, "It is strictly a performance car, and as such, does its job quite well." Stone puts things in perspective saying, now almost a decade ago, "The last of the Bosses, but in some ways the most user-friendly. Easy to drive, mountains of mid-range torque, and stirring performance. The top dog among the '71-73 Mustang models." Our take today? Of the last of the classic era-Mustangs, it is probably the best balanced of any from that series.

What will it cost you to add this car to your collection? Mecum gives no pre-auction guidance so looking at recent sales of similar Boss 351s, including a very similar car previously owned by NASCAR legend Bill Elliot that just sold for $70,400, we expect that a good guess would be from $50,000 to $70,000. For more details, check out the car's very comprehensive listing, which includes the car's Marti Report, at mecum.com.

Photography by Wes Allison