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

A Day Late: 1970 Mustang KK 429

1970 Mustang Boss 429

Yesterday morning I received an email about a 1970 Mustang that had just purchased. The new owner had found it the day before, pulled it home, and decided to find a new home for it with someone who could restore it. Just hours prior to emailing us, they threw it on eBay just to see if there would be any interest. Well before I even had a chance to email them back, the eBay listing had ended. Now I’m the curious type, so I wanted to know why a rusted out Mustang that clearly has been neglected would sell so fast. It wasn’t that the car was being offered for an incredible price or that it had any desirable parts left on it. It sold so fast because it is an incredibly desirable KK code car, which is also known as the Boss 429 NASCAR. If you’d like to see the original listing, find it here on eBay.


If you haven’t ever heard of a KK 429 NASCAR don’t worry, that’s because there were only 500 built. With Chrysler dominating NASCAR, Ford decided it needed a competitor to take on the Hemi 426. That lead to the development of a highly tuned 429 engine, but if you know your NASCAR history you know that Ford never actually ran any Mustangs on the NASCAR circuit. To make the 429 engine eligible for racing, all Ford had to do was sell it in 500 street cars. Since the Torino and Cyclone already had high performance street versions, Ford Brass decided to put the newly developed engine in the Mustang and call it the Boss 429.

1970 Mustang Boss 429

Now you might be wondering where the KK code comes into play. Well it isn’t an official Ford designation, but instead a code given to the Boss 429s to denote that they were built by Kar Kraft. The company had been building the Boss 302s for Ford, so it just made sense to have them also build the 429 cars as well. Fitting the massive semi hemispherical head 429 in the Mustang was no small task and took extensive modifications. The shock towers had to be modified to give the engine ample room and of course the suspension had to be beefed up to handle the extra weight. They also had to install a heavier duty transmission and just about every piece of the drivetrain had to be upgraded or reinforced to handle all the added power. Given their rarity and performance, it’s no wonder these cars are fetching amounts well into the six figure range.

Rusty Boss 429

The seller didn’t tell me how much the buyer paid for this Mustang, but I’m sure it was the kind of offer that none of us could have refused. I asked them to make sure the new owner gets in touch with me, so they can hopefully keep us updated on their progress. This would be one restoration I would love to follow, as it isn’t every day you get to watch an extremely rare and desirable Boss 429 get resurrected from the brink of decay. Hopefully they will get in touch with me soon! So who here has ever had the opportunity to experience the Boss 429?


  1. Mark in Medford

    I wonder if the engine is included ? The poor car looks like the sub frame rails are rusted to the point the car is sagging in the middle. I would love to see this Grabber Blue beast when it is restored.

    Like 0
    • rick

      The bay listing said no engine included. It sounds like there was no engine when it was purchased in the last exchange of buyer/seller. That’s a pity. Doesn’t say if the tranny is there tho, but I’d guess not.

      Like 0
  2. Jeff W.

    Went with my dad and older sister to the Ford dealer and she found one the same color as this one, but she couldn’t drive a 4 speed, so Pop’s takes he around the corner to the Mercury dealer and she picked out a 428 Cougar Eliminator, white with gold stripe and lettering….wish she still had it.

    Like 0
  3. erikj

    Well I’ve told this story before, but it one I will always remember: Around 1982 I worked for a fast oil change place in seattle. One busy Saturday things slowed up and I thought I can finaly crawl out of the pit for a break.Well all of a sudden a noisy beasty showed up . O shit dam back to work. It was just outside the bay ,a orange 69,or 70 mustang with a spoiler on the front was all I could see. It was shut off and they couldn’t restart it so it was pushed over the bay. I remember as is rolled over me The underside was incredible.ducting went to the huge front disks from the spoiler,all kinds of heaveyduty suffed under and soom huge rearend . As I started draining the oils the guy above called down to me and said I need to come up top and see this motor. I went across to our other bay to see what this mustang looked like. It was a fastback and those fender stickers: 429 boss. I didn’t know at the time what that was ,I soon found out I actually got to work on a 429 boss .I did talk to the guys that brought it in . It had been stored quite a few years,was raced and they had just bought. that’s why it was at our shop I,ll never forget that. We did our work on it and it still would not start so we pushed it outside . That was it, I really wanted to here it run but they towed it away and that was the last I saw of it.

    Like 0
  4. TuckerTorpedo

    Gotta wonder what this sold for, even missing the critically important original motor. Such rough condition, but so rare and significant. $25K? $50K?

    Like 0
  5. stanley stalvey

    Would like to see a lot more of this type automobile in Barn Finds.. The foreign cars are nearly impossible to get parts for..

    Like 0
  6. Dolphin Member

    I think this will be restored so it looks perfect. Somebody must have a hemi head 429 engine that is the proper engine for the car.

    Then it will probably be offered at B-J in Scottsdale. Excluding the original Ford GT40 and the recent Ford GT, this is the Ford with the highest price range in the current SCM Price Guide: $215K to $280K. No surprise the car was removed from Ebay so quickly. .

    Like 0
  7. Rancho Bella

    Having been in the Boss 302 (B2) world for many years (for those of you viewing the Mecum Houston auction last summer, the white B2 was my old one) , the 429 KKK never interested me as the weight distribution was so out of whack. B9 prices have sky rocketed. I reckon because they are not common.

    Like 0
  8. sunbeamdon

    Great find – hope this owner isn’t a “flipper” too!

    My Boss429 story is the result of a search in 1981 for a 427 Side Oiler for a customer car – rumour had it Severson Construction on Hiway 99 north of Seattle had one. Well, it wasn’t a 427SO, it was, in fact, a Boss 429 shipped from Holman & Moody in the winter of ’69/70 for Severson to put in his Nascar style race car. Problem is NASCAR banned the 429 so Severson had it stored in its original shipping crate behind a dozen or so tires and wheels for his heavy equipment. The “deal” – you move the tires, etc, and if you like it pay me what it cost from H&M. I had never seen a complete Boss 429 motor up close before – I was floored at the visual image. I made the deal – brought to the shop and tried to figure how to get it into a Jim Kellison Stallion Cobra – dry sump and all. Took some creative top frame spreading and sectioning the right frame-rail for the starter but got it in. My first “test drive’, with “Positraction” less than sticky tires, resulted in a more than sideways excursion (no damage). Our buyer drove it for very short period of time, couldn’t accept that it wouldn’t cool at the local hamburger stand and had Green’s r & r for a stove bolt 429! Green’s is rumoured to have used the Boss in their offshore racer.

    Now after reading the above, does anybody want to hazard a guess as to what I paid for this Hope Diamond of a motor?

    Like 0
    • Jamie Palmer Jamie Staff

      Ok, I’ll bite, Don…how about $2500 (only because you were paying what it cost in ’69-70)…?

      Like 0
      • sunbeamdon

        Hi Jamie: Absolutely – wait for it –

        Right! Add at least a zero today! It was a deal in 1981 I couldn’t pass up

        Like 0
  9. james g

    makes me wonder why did they take it off the road in 76 and what they did with the engine you can still see the weeds stuck in the front from being pulled out of the field

    Like 0
  10. james g

    to bad the car doesn’t look like this with only 13,400 miles

    Like 0
  11. jim s

    i hope it was bought to restore and not just for the VIN. great find

    Like 0
  12. Rocco

    I know a man that has a BOSS 429 engine sitting on an engine stand. When he bought his BOSS 9 years ago (’74-’75), he started acquiring extra engine parts. I remember him buying Holman/Moody or Bud Moore B9 parts around ’75-’76 from their leftover stash. He just recently sold the BOSS 9 with the original motor. So now he has an extra B9 engine, if the buyer of this car (or anyone)is interested.

    Like 0
  13. Wayne

    If you check the ebay listing, the car didn’t sell. The owner cancelled the listing. He was probably made an offer for it off ebay.

    Like 0
  14. Danger Dan

    Wow, if there is a boss 429 laying around out there, I will keep searching even harder. Theres hope yet lads!

    Like 0
  15. Hoby

    Never saw a Kar Kraft One Cool Find

    Like 0
  16. Mike_B_SVT

    This one was discussed a little bit over on the Boss forums, here: http://www.boss302.com/smf/index.php?topic=68556.0

    Like 0
  17. Cameron Bater UK

    This car is on my “Money no object list” (Every guy has one, don’t deny it)
    With such favourites as Dodge Charger Deytona, SS El Camino and of course the Mclarren F1 LM Longtail this list is strictly A-list. (HA)

    Like 0
  18. BrianZ

    Considering the way this car looks, I’d guess that the only way to save it would be a re-body. Someone will probably find a clean fastback and transfer the remaining salvageable items including numbers to the better car. I’m always amazed and confused by the mentality of an individual that would buy something like this and then let it deteriorate into a mess we see here.

    Like 0
  19. Dave Alzayer


    First nice article but I am the administrator for a big Ford site and I know my Fords and NASCAR history.

    1) Ford dominated NASCAR in the 1960’s. Ford won more races than anyone and won every Championship from 1963-69. Thats seven Manufacturers Championships in a row.

    2) Ford DID race Mustangs in NASCAR. The first time was this happened was at Talladega in 1969. The car was built by Smokey Yunick. His driver lead the majority of the race until a rocker arm broke.

    3) A Mustang actually won a NASCAR race beating the more aerodynamic Superbird. I think that race was in 1971 and the red Mustang was driven by Davey Allison. There is still a lot of controversy over that race.

    If you dispute any of this or want to learn more I can provide proof.

    Like 0

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.