427/4-Speed! 1966 Chevrolet Impala SS

Semantics are important and descriptions matter. Take this 1966 Impala SS, the listing claims it as a true SS 427 car. Well, it’s really an Impala SS with a 427 engine, as an Impala SS427 was specifically known as RPO Z24 and was available from ’67 to ’69. It matters from a perspective of collectibility and value. But there is more here to that story too. Let’s take a closer look at this Everest, Kansas domiciled Chevy, it’s available here on eBay for a current bid of  $7,600, reserve not yet met. Thanks to Larry D for this tip!

So, how do you know what you really have in a case like this car? Well, the VIN authenticates is as a ’66 Impala SS, with a V8 engine, produced in St. Louis, MO, and the trim tag places the assembly date as being the second week of February. So, how about the engine? That’s a bit harder to figure. The obvious determination is made by decoding the engine’s alpha code and verify that the engine’s sequence number matches the VIN’s sequence number. The VIN, however, will not define the born-with engine, that change didn’t happen until model year 1972. The build-sheet can lend some assistance on this front too.

The seller claims, “1966 IMPALA TRUE SS 427 CAR” and then adds, “ENGINE NOT LOCKED UP…..TOOK PICTURE OF STAMP CODES ON BLOCK, THINK ITS 454 BIG BLOCK“. OK, so it’s a youstabee? It used to have a 427 engine but does no longer? Is it an original 427 car? Absent the build sheet, we’ll have to take the seller’s word for it. But wait, interestingly, the engine’s Alpha code, as revealed by the supplied image, is “IH” which is a ’66-’68 427 CI V8 engine coupled to a manual transmission, and the seller, later in the listing, acknowledges as much! Owing to the uniqueness of the harmonic balancer for the externally balanced 454 engine, and how it would line up with a pre ’69 pulley system, I doubt that this car harbors a 454 ci motor. A 454 would have a triple alpha code and this engine’s cylinder heads look like the pre ’69 variety. It is a non-runner, though, as it’s disclosed that the carburetor is MIA. The concerning thing is the fact that the manual transmission, in this case, a four-speed, is in the trunk along with the shifter, clutch, and bell housing. Why? Good question.

I know from personal experience, a ’66 Impala can be a real rust bucket. This example, however, seems to have escaped that fate, for the most part. Other than the trunk pan and the lower quarters, the body of this Impala appears to be pretty sound. There are a few minor body contusions and the front bumper, like mine, has been pushed up and in a bit. The Aztec Brown (Code M) finish shows to be original and is pretty worn but that’s to be expected after the passage of 55 years. The Chevrolet mag-style wheel covers are a nice touch but they’re not included in the sale.

The interior is a typical Impala SS black vinyl, bucket seat interior with a center console. This Impala has the optional gauge package which includes amps, engine temperature, oil pressure, and vacuum. The seats are starting to split and the carpet has seen better days, but it’s all easily repairable as replacement “everything” is available for a ’66 Impala from multiple sources.

This Chevy appears to be a  flip owing to the lack of knowledge around the engine’s specifics but then, so are many of the cars that are found under similar circumstances. While the engine appears, both physically and via code to be a 427, it’s not the original engine. Nevertheless, a big-block, ’66 Impala SS models with a four-speed manual transmission can bring sound value so this is a Chevy with potential. Now if I only knew why the transmission was in the trunk…

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  1. Bob

    ” – The Chevrolet mag-style wheel covers are a nice touch but they’re not included in the sale.” Thank God ! – those aftermarket fake Mags are about the ugliest useless weight you can put on a car . I had a buddy who bought a used 327/365 HP stingray with these and I told him to feed them to a dumpster before I’d ride in the car.

    Like 23
    • Skorzeny

      Bob, agreeing wholeheartedly.

      Like 2
    • Jim ODonnell Staff

      Do you know which dumpster? They sell for north of $400 a set these days.


      Like 33
      • Jerry

        Actually They are not aftermarket as in a JC Whitney catalog. They were a factory ordered option. I bought a brand new set of the same at a yard sale in 1987. For $25.00. Wish I kept them stored away instead of using them.

        Like 7
      • Jim ODonnell Staff

        I know that, RPO N96, that’s why they’ll bring over $400 a set today. They were made in 13″ (Corvair) & 14″, I’m not sure about 15. I have also seen some with black spokes. I bought a set in ’73 for $25, used, with some road rash, and sold them later for $100. I wish I still had them.


        Like 4
      • 427Turbojet 427Turbojet Member

        15″ covers were made, not sure which years. My Dad bought a new Impala Custom Sport Sedan in 1970 with 15″ mag covers. If the previous poster’ buddy had a Corvette with these they’d have to be 15″. I have a couple of sets of 14″, one set will go on my Aztec Bronze ’66 Chevelle convertible. Or maybe sometimes use the wire covers with the spinner. Kind of a nice change from the typical mag wheel and very easily changeable.

        Like 6
      • John

        Let me know which dumpster. I would love to have them.

        Like 3
    • CCFisher

      They aren’t aftermarket covers, they’re genuine Chevrolet items.

      Like 10
      • John

        There were two similar style Mag cover made by Chevy. One is 65-66 and the other 67-72. The 65-66 are more costly

        Like 2
    • Chuck Dickinson

      Sorry, Bob, those are NOT aftermarket mag covers. Chevy introduced those in mid-65 to supplement the optional wire caps. They were often shown on 66 Chevelle SS 396s. Like ’em or not, those are a factory optional wheelcover.

      Like 9
  2. JCA

    Another seller who can’t take good pictures let alone spend the extra $2 to put up 20+ pics that this car deserves. And why not put the engine code in writing in the description so knowledgeable people can figure it out? Crazy

    Like 10
  3. Norman Wrensch

    These models also had big frame rusting issues, body can look decent but frame can be junk. I had a 68 like that.

    Like 4
  4. Maverick

    Agreed. The other 67 impala listed on barn finds has me wondering. I have had 65 68 impalas .look good bad. frames

    Like 1
  5. Joe

    This car needs some research….

    Like 1
  6. Chris R

    The tail lights are all one color. That is a Caprice. Impala had the back up light center that was white. Caprice models and the Impala grand prix had the biggest engines. Looking at that engine. I would say 385 horse 427. And if the back up light lens was not replaced. A Caprice. HP 427 4 speed Caprice were special order and lot of them produced. It is rare. Not that rare. With over 2,000 produced each year from 1966 to 1969. With the center console. The tranny should be not be an muncie. Non console cars had the muncie. But if you had the tanny code for a muncie when it was ordered. It could have a muncie. The car is well worth more than the current 7,600 bid. In present condition. Should bring around 20,000 easily. When fixed. Around 60,000 to 75,000.

    Like 3
    • MathieuB Member

      Caprice were only available in Custom Coupe not Sport Coupe.

      Like 5
    • Jim ODonnell Staff

      The lenses are correct for an Impala. The backup lights are in the bumper, note the attached sales brochure image, the top picture is an Impala.


      Like 11
    • Mike

      Chris, The tail-lights on this car are Impala. (actually, on the Impala/Caprice, the back-up lamps are located on each side of the license plate, and are not part of the tail light).
      The Caprice tail-lights differed from the Impala, with 2 chrome-like
      horizontal ribs in each tail-light.

      Like 2
    • Robert Brandt`

      And the color is Aztec Bronz ,

      Like 2
    • Craig

      No, all Impala’s had “all” red taillight lenses with backup lights in the bumper, I’ve owned enough of them and currently have a 66′ Caprice coupe. Caprice’s did, however have chrome trim on the taillight lenses that Impalas did not, so they were different but none had backup lights in the taillight section. The Bel Air & Biscayne did have a backup light on the trunk section of the taillight lenses though with nothing in the bumper, so you may have been thinking that or someone put a standard bumper on an Impala and got aftermarket taillight lenses. Chevrolet had the center lenses for the backup light in the 1965 and then went back to it in 1967, with the 66 as a stand alone year without it (I think too many got crunched in bumper bumps in the 66’s).

  7. MathieuB Member

    Rust is much present beneath the cowl tag, not a good sign.

    Like 1
  8. Ben

    This car is a oval port 427 car not an L72, look at the tach, low redline, lots of nice option thou,

    • jerry z

      I’m sure too that this is a 385hp car. Wonder if any documents hiding in the car.

      • Craig

        As far as finding documents in a 66 SS or 66 Caprice with buckets, I always found build-sheets under the carpet somewhere, one in the back of each bucket seat when you take off the back metal seat cover and usually one tucked in the springs under the bottom of the rear seat. Four of them found in the car I have now.

      • Kirk Aldrich

        In 66 the low horsepower 427 was rated 390 not 385, 1967 they changed it to 385. And all big blocks 4-speeds had Muncie’s, and a very few L72’s has Muncie M22, very rare. Some of the small blocks used the Saginaw 4-speed trans. I had several 65-67 big and small block Impala’s, including a 66 L72 4-speed with F41 suspension, and a factory installed 4:56 rear axle.

        Like 1
  9. Karen

    Where are you ? Been in the market for a good weekend car. Does it run? Ever figure out why the transmission is in the trunk Lol ?

  10. Kevin

    Clearly a project car,and one should expect to rebuild the engine, transmission,and braking system before serious use,and only if frame is not rotten, would I even consider this project, this could be a nice car with a solid frame, and big enough budget,and personally I’d put rally’s, or cragar s/s wheels,matter of taste on that one.

  11. Storrer

    Wonder what is holding up back end of the engine?

  12. 4spdBernie Member

    For comparison, here’s a genuine documented numbers-matching 427 4 speed ’66 Caprice in the same beautiful Aztec Bronze -> https://www.youtube.com/watch?v=8MYqqu5Dkpc

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