Some of the most fascinating automotive stories simply come from the intricacies of running a massive multi-national corporation like General Motors. Rules, olicies, ngineering edicts, nd other guidelines ensured uniformity and a strict adherence to the Alfred Sloan hierarchy, ut creative folks could always find a workaround. But sometimes, M did it to itself, reating something, hen hiding it from the public. The L88 427 Corvette was such a situation, here Chevy hid it in plain sight by giving it an artificially low horsepower rating and a huge price tag to coax buyers into buying a more street-friendly and affordable L71 427/435 instead. But sometimes—sometimes—they just built something then forgot to tell anyone about it at all, nd that’s the case with this 1969 Chevrolet Impala SS427 convertible.

If you wanted an Impala SS in 1969, 427 was the only engine choice. The standard engine was the L36 which made 390 horsepower with a hydraulic cam and pretty friendly street manners, deal for a big luxury car like this. A lesser-known option was the LS1, hich made a relatively tame 335 horsepower. But for reasons that aren’t altogether clear, here was a third 427—the legendary L72 425 horsepower version—that GM decided the public didn’t need to know about. No advertising promotions, o mention of this motor in any of the promotional and sales materials, nd unless you were sharp with the order form, ou probably didn’t even know you could get such a thing in 1969, ecause Chevy certainly wasn’t talking about it. A total of 546 L72 engines were built and they were installed in a variety of Chevy vehicles (they were not exclusive to the Impala, ou could get it in your Kingswood station wagon if you were savvy), aking them quite rare. Mission accomplished, hevrolet!

This incredible 1969 Impala SS427 convertible is a real-deal L72 car, urchased new by John Cornstubble (no, ’m not making this up) of El Dorado Springs, issouri on May 12, 969. The number of L72 Impala SS427 convertibles built can probably be counted on one hand, aking them some of the rarest and most highly-sought of Chevy’s heavy cruisers. Even more significantly, his one is fully documented, ith original purchase documents, rotect-O-Plate, nd receipts from nearly five decades of life. It still carries its original, umbers-matching L72 427/425 engine and TH400 3-speed automatic transmission, nd was recently treated to a cost-no-object restoration by the pros at Boot Hill Automotive Resurrection in Toronto, ntario. We have photographs documenting, ell, ust about everything as well as significant ownership history and photos of the car in-period. This car has one heck of a pedigree no matter how you look at it.

Here are the relevant details:

Protect-O-Plate:

164679S (037146) Production # 1: Chevrolet Motor Division 64: Impala 8 cylinder 67: Convertible 9: 1969

T0907LS T: Tonawanda 0907: September 7 build date LS: TH400 for Impala SS 427/425 Hi-Perf L72 69Y275: Build date of the TH400 transmission, ctober 1st of 1968 (275th day of 1969)

DK1015G DK: Posi-Traction 3:55 Large Ring G: Detroit Gear and Axle 1015: October 15, 968

1: Power steering 1: Power brakes 3: AM radio 3: Front disc brakes

Cowl Tag:

69: Model year 1969 1: Chevrolet Motor Division 64: Impala 8 cylinder 67: Convertible

STL: St. Louis assembly plant

138170: Sequence number

858: Parchment vinyl bench seat 65: Olympic Gold B: Black vinyl convertible top 10C: Third week of October build date

In person, he restoration is simply spectacular. Olympic Gold is this car’s original color and it works rather well on the full-sized ragtop, ffering just the right combination of flash and elegance. The car appears to have been extremely solid prior to the restoration and as far as we can tell, t’s still wearing all its original sheetmetal, ncluding floors and quarter panels. The big doors open and close so easily and precisely that your first few slams are a little too hard, nd the hood latches with just your fingertips. The two-stage urethane paint has a fantastic shine complements of some of the best guys in the business, nd it has been color-sanded and buffed to a fantastic shine. All of the correct emblems are in place, nd yes, or those of you wondering, hat stick-on deck lid ‘SS’ is how the factory did it. The bumpers have been refinished, he stainless is polished, nd if there’s any demerit on the car, ne of the wheel arch moldings has a few minor dings in it, s it is surely original. But there just aren’t many nits to pick on this gorgeous car.

The cowl tag says this car original carried a Parchment interior, ut when it was restored it was treated to a correct black interior instead, nd the contrast is striking. Obviously, s a color change, verything in the car was replaced with a brand new piece, ncluding the seat covers, oor panels, ide panels, nd all the little detail pieces in between. The dash pad is excellent and the carpets are brand new, eplicating the original weave. The upscale Impala also received some warm-looking faux wood accents that perfectly match the woodgrained steering wheel, hich sits on an optional tilt steering column, rather rare option, S or not. This car also carries factory power windows, hich is a very desirable feature in a big luxury car like this, nd the wide bench seats mean there’s plenty of room for everyone when you go cruising. The gauges show bright, risp markings and we strongly suspect that the 43,500 or so miles shown on the odometer is correct, s it was not rolled back during the restoration. The only notable deviation from stock is a later digital AM/FM/cassette stereo radio in the dash, ut the original pushbutton AM radio is included with the sale of the car if you’d like to take it back to 100% stock condition. The top is brand new black vinyl with a correct glass rear window, nd it powers itself up and down easily, atching at the header without a struggle. It fits beautifully and we suspect that our photo session was the first time it’s ever been down.

The good stuff is all under the hood, owever. The L72 is the real deal, ith a fantastic big camshaft idle and a torque curve that feels like it could pull forever. While someone with true performance intentions might have purchased a Chevelle or even a Camaro in 1969, ucky Mr. Cornstubble got a full-sized luxury car that hits several levels below its weight class, ecause it is surprisingly fast. The engine was fully rebuilt to stock specs and still carries its original cylinder heads and correct aluminum “Winters” intake with a big Holley 4-barrel up top. It starts easily and while it’s a bit grumpy when it’s cold, t is nevertheless content to idle all day and sits in traffic without getting cranky. The engine bay is detailed for show, ith Chevy Orange paint on the block itself and proper fasteners and hardware throughout. There are some who say that the L72 should have an open-element air cleaner, ut it appears that this air cleaner has been on the car from a very early age, erhaps even when it was new, nd the original chrome valve covers were replaced with painted valve covers simply because the owner liked the low-key look better (the original chrome valve covers are included with the car). An Optima battery provides the juice and makes the big, igh-compression V8 spin over easily, lthough it’s not 100% authentic, f course.

Underneath, he original TH400 3-speed automatic transmission was rebuilt and bolted to the back of the 427 and linked to a heavy-duty 12-bolt rear end with 3.55 gears and a Posi limited slip unit inside. Much of the suspension features upgraded Hotchkis components, ncluding a pair of seriously beefy sway bars, ecause the intention was to build an L72 that would be a blast to drive. You’ll also find a beautifully crafted stainless steel exhaust system with welds that should be on display in a museum; it’s just beautifully done. The floors, rame, nd suspension components are in exemplary condition with correct hardware used throughout, o it wouldn’t take much to put this car into 100% original, how-worthy shape, ut it would truly be a shame to take it off the road. Simple color-matched steel wheels with “dog dish” hubcaps were how this car came from the factory, o they were cleaned, ainted, nd fitted with fat 235/75/15 Coker redline radials for a period-perfect look.

Documentation is pretty extensive. There’s the original Protect-O-Plate and service booklet, anuals, nd an album full of restoration photos, ll of which will accompany the car. This is quite likely the finest of its kind anywhere, nd with a strong pedigree and equally strong performance, his awesome Imp makes for the best kind of hobby car.