Disclosure: This site may receive compensation when you click on some links and make purchases.

Convertible Firebird??? 1975 Pontiac Firebird

Custom convertibles tend to make many enthusiasts nervous, as lopping the top off of a fixed-roof car can sometimes have serious consequences on structural rigidity. Few companies among the aftermarket ever mastered the skill at a respectable level, aside from the likes of OEM suppliers such as ASC. That’s why this 1975 Pontiac Firebird here on eBay is so intriguing, as the seller mentions it was converted to a convertible by a California company but fails to mention which one.

That detail is a big deal in the case of a car like this. Was it a respected OEM partner? A really good independent that didn’t cut corners? Or was this done by any number of conversion shops that were more known for installing pop-up sunroofs that began leaking within six months than for designing a custom soft-top that fit the contours of the car and kept the occupants dry.

It’s hard to know for sure, as there were a few different companies offering this service. American Convertible Corporation was one, and National Coach Engineering was another. The latter was in Michigan and apparently had a close relationship with the factory. American Convertible Corp. also converted Mustangs of the same era, and with a heavy markup in price for the soft-top version of either car.

Although there’s a 400 under the hood now, the seller is also including a spare 455 motor. He had grand plans to make it into a Super Duty soft-top tribute, but those plans failed to launch. The automatic transmission would be swapped out for a manual if it were mine, and that 455 absolutely dropped in. There are no bidders right now at the strong opening offer price of $6,000, with the option to Buy-It-Now for $12,00o.


  1. NotSure

    Absolutely positively insert the 455 with a 4-speed behind it! But of course the concern that the car may not have been a sound conversion gives great pause. Is the Seller now expensively educated on the car and now wants out of this folly or has he just lost the will to finish it out? Proceed with caution.

    Like 11
    • Mike W_H_ Mike W H Member

      Sure, now that you’ve destroyed the integrity of the unibody by cutting the top off, put a motor in that will torque that car into a knot.

      ” I don’t know why the front end flexes right like that “

      Like 8
      • NotSure

        Could install the 400 next to it and backwards? Maybe that would balance the torque??

        Like 3
      • Joe

        Subframe it. It’s done all the time.

        Like 0
  2. edh

    So the reason for not taking a full side view shot of this vehicle?

    Like 15

      Because he instantly came to realize that some cars were never meant to be ragtops.

      Like 8
  3. CCFisher

    It survived 44 years without folding in on itself, which has to count for something. The top appears to snap to the exterior surface of the body, but that was common for conversions, as there were no provisions for drainage built into the body as with a factory convertible.

    Like 2
    • Miguel

      CCFisher Those snaps look like they are for the top cover, not the top itself.

      A lot of factory convertibles has those snaps.

      Like 1
  4. Little_Cars Little Cars Member

    This car looks shoddy from the limited and fuzzy photos, including what we can see of the front header, top frame and well. Otherwise just another red repainted, rusty framed, ragged out T/A from the Northeast. If the convertible alteration was such a premium the seller should have honestly taken the car out into the sunlight and shown it with the top up and down. Way overpriced for a mystery conversion. I’d love to find a base or Esprit with the convertible conversion done properly. Have had a model car of second gen Firebird and Camaro convertibles in my collection for years.

    Like 4
  5. redwagon

    Intriguing concept but it all depends on the execution of the chop top and current condition of the vehicle.

    I’m not certain what would be cheaper, or the better approach, to build the 455 or bore out the 400 and build that. I suspect much would depend on how robust the 455 is and there are few pictures to make that determination.

    Why no full side picture in the add? Pure laziness is my guess. It would take too much work to get it out, photograph it properly and then put it back in the storage box. And yet, if someone is really interested in this thing it will have to come out.

    Like 2
  6. Jim

    Ads punctuated with exclamation points on every sentence leave me exhausted!!!!

    Like 6
  7. OhU8one2

    Go on keep your money and run.

    Like 6
  8. KevinLee

    Never liked the looks of the 1970s or 1980s Firebirds minus the hardtop!!! Y’all have a good day!!! MY NAME IS KEVINLEE!!!🤣😁

    Like 0
  9. Steve R

    An opening bid of $6,000 with a BIN of $12,000, that a big ask for a car that worth closer to $1,500-$2,000. I hope he’s prepared to sit on this until the end of time.

    Steve R

    Like 6
  10. blyndgesser

    Even with a roof, the structural integrity of the 2nd generation F-body was iffy. I really don’t want to drive a limp egg noodle with 300 hp.

    Like 4
  11. 408interceptor

    First generation F-bodies came from the factory as convertibles but the second generation did not. Structurally both designs were similar with a front subframe bolted to the unibody. Does anyone know if GM added structural bracing to the original F-body convertibles?

    Like 1

Leave A Comment

RULES: No profanity, politics, or personal attacks.

Become a member to add images to your comments.


Get new comment updates via email. Or subscribe without commenting.