My Car Quest

June 12, 2024

Editorial: A Matter of Pedigree

by Wallace Wyss –

It is oh-so-fashionable nowadays to do a DNA search to see if you have any relatives you didn’t know about. My own niece did it and discovered she had a half sister. Well, cars have DNA too. Sort of.

So when I saw this 427 Cobra chassis advertised for sale in Michigan on Bring a Trailer I began to think about whether any Cobra built on this chassis is an AC built Cobra. One thing that gives me a moment of pause is that BaT reprints a bill of sale from 1970 where the seller calls it a “Cobra.” It was a no sale with a high bid of $37,502 on July 19, 2022.

Yet it has no SN of the CSX3000 series which is what Shelby big block Cobras fell into whether they were 427 or 428. There is a SN mentioned in a second sheet from the seller EFX502. Not a known Shelby series. Then there’s a copy of a check on BaT for $2700 written back in 1970. But in the BaT story there’s no paperwork from AC Cars, Ltd saying what the SN the chassis bore when it was sold to the electric car company.


From Bring a Trailer

I say it make all the difference. If it is a leftover chassis built for Shelby, sent to Ford, and then Bob Negstad, the Ford engineer, at the time free lancing a project for the Electric Car Propulsion Company connected them with to the leftover chassis. Plus to roil the waters more didja know that for a Hollywood comedy The Great Race four more chassis were ordered to be rebodied as 1920’s cars. What happened to them? What chassis numbers did they have?

To me it is a Cobra chassis re-purposed. I don’t know who has a full record of AC’s SN log of what they built and sold. If their records show they had CSX 3000 series serial number when sold to the movie company I’d say they were Cobras. If they had AC number at least they were blood relatives.

So here’s the anti-Cobra argument. There are other cases from other automakers where cars were built that start out with an existing chassis design when some new automaker asked to buy the bare chassis and built their own car on the chassis. For instance the Ghia 450SS I used to think it was a Barracuda chassis but now think it used Barracuda mechanicals but its own frame.

The Stutz Blackwak used a variety of chassis, even a Firebird chassis, and changed make of engine each time they changed chassis but they were still titled Stutz Blackhawks.

So the answer to whether the chassis on Bring A Trailer is a Cobra depends on if AC Car Ltd. made it up for Shelby to sell, or if AC made it for themselves to sell, as the AC 428 or as the Frua Spyder. Either could be shortened 6″ and rebodied as a Cobra and if there’s a record of it being made as an AC chassis that was numbered I’d recognize as near kin to Cobra (“A brother from another mother?) a car with the same DNA so to speak.

Just as AC Mk. IVs are recognized as Cobra kin to me. Same design as from Negstad of Ford. Chassis made, and body pounded out, at AC Cars.

So there’s the situation. I still remember reading of when some old pre-war Roll Royces in the UK were re-bodied as farm tractors. Sacrilege? No, necessity. If one could prove they came from Rolls with chassis numbers from Crewe originally they could still be rebodied as Roll Royces. So it’s all in where the chassis was born that convinces me.

What say you?

Let us know what you think in the Comments.

Wallace Wyss art

THE AUTHOR Wallace Wyss, a fine artist, is offering oil portraits of significant Cobras. For a list write


AC-Logo 2

Editorial: A Matter of Pedigree
Article Name
Editorial: A Matter of Pedigree
When I saw this 427 Cobra chassis advertised for sale in Michigan on Bring a Trailer I began to think about whether any Cobra built on this chassis is an AC Cobra.


  1. So true. Last June this 1959 Astin Martin:
    sold for $33K. I’m not even sure you could call this a parts car? It was in a fire and all parts were shot. I was told someone would buy this for the vin tag and rebody it.

  2. Eric Cashdan says

    A Barracuda would have been unlikely to be rebodied as it was a “unibody” structure. I believe that the 450SS used Barracuda “Formula S” mechanicals on a purpose built chassis.

  3. Glen Durmisevich says

    The Classic Car Club of America has a category for rebodied cars since many classics were rebodied when fairly new, and if the chassis and engine are authentic even a newer rebody can be certified.

  4. Rob Krantz says

    There was quite the spirited discussion on a Cobra Facebook forum about this chassis, EFX502. It’s not a CSX, COB or COX chassis number and the FB discussion, with some very involved and well informed people, went into a lot of detail on this chassis. Unfortunately, I’m unable to find the discussion anymore on FB. In any event, a few chassis were purported to have been built by AC Cars for Electric Fuel Propulsion of Michigan to build some electric cars. I don’t believe any of those cars were ever built. In the FB discussion, a member of the Hurlock family, which owned AC Cars in the 60’s when the Cobra was produced, adamantly stated that AC never made these chassis. His source of course is his own experience growing up in the AC world when his father helped run AC and who is still alive and said they never made these EFX chassis. So, it’s a mystery I guess.

  5. wallace wyss says

    I came across this letter from 2008 on a AC Owner’s Club register

    It appears that what some collectors fear is already happening–aging 428 Fruas are being cannibalized for their chassis, which once shortened 6″ in wheelbase, can accommodate a 427 Cobra body. On an AC Owner’s club website I found one such case but they mention this fate awaits other 428 Fruas that are rusty or otherwise undesirable…

    08, 11:38:40 »
    Hi David

    Both conversions already known and listed thanks in a first draft AC 428 Register I cobbled together late last year, which the Club has since removed to be replaced hopefully with their glossy on-line version sometime soon. [8D] I can attach a copy to an e-mail if you need.

    To bring you up to date….


    Extracted and copied across from old Register I’ve saved on hard drive :

    CFX 35: Fastback. Automatic. Now 428/ Cobra Conversion.
    Manual. LHD. Trade advert: La Baule, Brittany France.
    Status: Active.
    E-mail received 5/1/08.
    “Dear Sir,
    the car we have for sale is a conversion from an AC Frua 428 to an AC Cobra
    427. The engine is not the original 428 but a 302 that has been fully
    prepared and that devellops 450 HP. The body is a SC one. The chassis
    number is CFX 35. Aluminium oil and water radiator. Aluminium vapor oil
    Tank. Aluminium water expansion tank. Special laiton 3 discs clutch. Gearbox
    is a toploader close ratio, wheels are original Halibrand with Hoosier
    Price is 200 000 €uros.
    Sincerly yours,
    Nicolas QUERARD
    PH : 00 33 2 40 24 10 36”

Speak Your Mind