1970 Ford Mustang 428 Cobra Jet Convertible

This car, Lot 1094.1, sold for $396,000, including buyer’s premium, at Barrett-Jackson’s Scottsdale, AZ, auction on January 24, 2025.

The late 1960s and early ’70s were a time of almost unlimited choice for car buyers. In the youthful, “sporty” segment of performance cars, shoppers were spoiled for choice by models from seven marques, and each car offered a wide array of engine choices and options. Ford’s Mustang was the segment leader since its April 1964 introduction, a model that could be ordered as anything from the proverbial “secretary’s car” to a track- or dragstrip-ready race car.

The 1970 Mustang sales brochure listed nine available engines. There were two inline-6s and a pair each of 302-, 351- and 428-ci V8s. The top of the line was the 429-ci V8, a NASCAR engine shoehorned into a few Boss 429s. Advertised horsepower for the engines ranged from 120 to 375; however, the larger engines were known to be putting out much more power, common practice at the time.

That year saw new-car sales decline across the industry, with Mustang sales down by a third. Still, 190,727 rolled out the doors, with the Mach 1 continuing its reign as the most popular after the basic hard top. Convertible sales were down 50% to 7,820.

Choices, choices…

Like the base coupes and SportsRoofs (Ford-speak for fastbacks), the drop tops could be ordered with any engine other than the 429. That engine choice is what makes our subject car different. Out of those relatively few convertibles, just 47 were produced with the 428 “Cobra Jet” (nine were also produced with the drag-racing-optimized “Super Cobra Jet”).

Getting deeper into the details, the 428 could come in either “Q-code” (as noted by the second letter in the VIN), or “R-code” variants. The engines were basically identical, rated at the same 335 hp. The difference came in the induction systems. The R stood for ram air, via a hood scoop or the shaker-hood option. Q-code cars breathed through a regular air cleaner.

The seller notes that during the car’s time with a long-term owner, it was restored to generally factory condition, with the exception of switching to a ram air setup with a shaker hood. This effectively turned the car from a Q to an R. This would be a simple operation, as back in the day you could buy the necessary parts over the dealer parts counter. (In this case, we don’t actually know where the parts were procured.)

While possibly increasing the car’s appeal, however, this conversion actually makes this example less rare. There were 33 R-code convertibles produced in 1970 (18 with the automatic), more than twice as many as the 14 Q-code convertibles (nine automatics). To the casual observer, that may not seem like a big deal, but to serious collectors, details and production numbers matter — whether you’re talking about Prancing Horses or pony cars. Given the seller touting the rareness of the car, it’s surprising that it hasn’t been returned to stock.

It was 20 years ago today

It’s important to note that this change happened under the care of a previous owner, who was said to have purchased the car in 1990 and had it restored shortly thereafter. It was a different world back then. The car was only 20 years old, NOS parts were more common, and originality was less of a concern than today. It seems likely that the hood was replaced with a Mach 1 part since the car has the twist-style locking hood pins that were standard on that model. It could be NOS, used, or even a reproduction; hopefully, such details are included in the paperwork file that came with the car.

Despite the age of the restoration, the car presents in as-new condition. The factory-correct paint looks fine and the car has excellent bodywork, though the right door seems to be a fraction of an inch high. The deluxe interior is factory correct, and although we don’t know how much of it is original, one of the seat belts has its original Ford tag, which is promising. The vinyl top is well fitted with a clear window. The engine bay is spotless, though it lacks most of the factory decals and is fitted with a non-OEM battery. No photos were provided of the undercarriage.

One major deviation from factory correctness is that it has a Mach 1-style hood stripe and “428” graphics. Along with the aforementioned hood locks, this would not be found on a stock convertible. To the cognoscenti, this example comes across as a car restored to taste instead of correctness.

A record price

At nearly $400k, to call this car well sold would be an understatement. The price here easily eclipses that of any stock Mustang convertible by a sizeable margin. For example, a 1969 428 R-code convertible with a detailed and factory-correct restoration brought $181k at last year’s Mecum Indy sale, which is about what we might have expected here.

This sale also handily beats the most expensive convertible in the SCM Platinum Auction Database, one of five specially modified pace cars built for American Raceways Incorporated for use at the Atlanta International Speedway. It was well documented and featured performance enhancements; it sold for $220k at Barrett-Jackson Scottsdale in 2022 (SCM# 6950662). Our subject car’s price even eclipses the $150k–$200k SCM Pocket Price Guide value range for the similar 1969–70 Shelby GT500 convertible, which typically trades near the top of the Mustang convertible market.

There is no denying that any 428 Cobra Jet is a desirable muscle car, and convertibles are especially rare. Regardless, this sale is an outlier. Rather than telling us about the state of the Mustang market, it serves more as an example of why in-person auctions still have a place in the collector car world. The excitement and drama of a live event can — and will — lead to sometimes-extraordinary results. ♦