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Chevrolet spent most of the 1980s selling the Corvette with a manual gearbox that most people have since forgotten: a four-speed with an automatic overdrive tucked behind it, built by a former drag racer and known as the 4+3. This 1988 Corvette convertible on Hemmings has one. It shows about 70,000 miles, and as of Wednesday morning, November 4, it sits at $6,000 with roughly five days left.
What the Doug Nash 4+3 Actually Was
The 4+3 paired a four-speed manual with an overdrive unit that worked automatically on the top three gears. That is where the name comes from: four gears, plus three overdrive ratios layered on top. It was offered in the C4 Corvette from 1984 through 1988, and when the overdrive was working, it gave the car a lower-revving highway gait than a plain four-speed could. Accounts of GM's motive generally point to fuel economy.
The reputation was mixed from the start. Period critics found it clunky next to a conventional manual, and the overdrive section developed a name for failing. When it did, the car did not strand its driver. It simply behaved as an ordinary four-speed with no overdrive.
The Drag Racer Behind It
The gearbox takes its name from Doug Nash, a Detroit-area hot rodder who drove the wheel-standing Ford Bronco funny car known as the Bronco Buster before founding Doug Nash Equipment & Engineering. According to a transmission-industry account of the design, BorgWarner stopped making four-speed manuals in the late 1970s and sold the specifications for its Super T10 to Nash. Chevrolet then asked him to develop the 4+3 from that foundation, and the design went to GM.
Why It Disappeared
For 1989, GM dropped the 4+3 in favor of a six-speed manual from ZF of Germany. The ZF box had two overdrive gears and electronics that could lock out second and third under certain conditions, a quirk of its own, but it was the transmission that carried the Corvette through the rest of the C4 run. That includes the last cars, like the 1996 Corvette Collector Edition with LT4 power and a six-speed. After 1988, the Nash box was gone, and the 4+3 has been a footnote ever since.
About This 1988 Corvette
The Corvette is one of 7,407 convertibles built for 1988, a figure that matches published production totals. It carries the 5.7-liter L98 V8 with Tuned Port Injection, rated at 240 horsepower and 345 lb-ft of torque when new. The listing shows 70,377 miles, a clean Illinois title, and a white convertible top over saddle leather. A clean Carfax report is included, according to the listing.
The seller, posting as Arch524 in Chicago, describes the car as original-condition and says the white paint is original. Those descriptions come from the seller, and Hemmings notes that it has not verified listing details. The seller also says recent work includes a new battery, an oil and filter change, an A/C leak test and recharge, and new clutch master and slave cylinders, and that an OEM exhaust was installed at about 68,000 miles. The seller reports no body damage or known problems. As with any 4+3 car, it is worth asking how the overdrive behaves on a test drive, since that is the unit that gets the attention.
The listing also notes an original sticker price of $34,820. Bidding stands at $6,000 after two bids, so this is not a case of a six-figure collector car. It is a solid, drivable C4 convertible with an unusual gearbox story.
Why It Is Worth Noticing
C4 Corvettes have long been the affordable corner of Corvette ownership, and the 4+3 is the kind of detail that separates a car people drive from a car people just own. Few enthusiasts remember the Doug Nash box, and fewer still have shifted one. If you want a look at what else is out there in the same corner of the market, 10 of the coolest Corvettes for sale on Motorious right now is a good place to start. And if Corvette-based oddities are your thing, the Cadillac XLR is another one most people forgot.
The full listing, photos and bid history are on Hemmings.
