It seems like most have that issue, I've owned mine since 1972 when I returned from my first tour in Nam. As the years went on, I yanked the drive-train. I kept it all just in case, I want to return it to it's original status. So I went hunting, and found a 1971 MACH1 with a 429 SCJ that was wacked just hard enough to tweek the frame. The insurance company ended up totalling the car, but the guy bought it back and I made him an offer which he accepted. I ended up keeping the drivetrain, and parting out everything else that was still in good shape. It was an 8 or 9 year project, after I got out of the Marine Corps which I ended up doing 2 tours in Nam and 7 years all together, from 1970 - 1977. Things kept changing in the project, which drove my wife crazy and as time went on I would seem to stumble on another I just had to take home. Anyway, the engine was torn down and the block and heads sent off to the machine shop, while there I started collecting a list of parts all forged to place inside the block when it was complete. At a distance it still looks stock, even the custom made 17" 500 wheels except when it was running it had this strange whine to it. I converted it over to fuel injection with a set of 1/2" fuel lines and 60 lb. matched fuel injectors. I placed a Viper 6 speed behind the motor for better fuel economy, an aluminum fly-wheel and drive-shaft and a Currie 9" with an Auburn center section with 4.30 gear set and 35 splined axles. Under the hood is an F-2 Pro Charger with after cooler for a denser air charge, works great it's been detuned for better street manners with a custom ground solid roller blower cam. When I went to put it back on the road, my wife said she would take care of it and I agreed to keep her happy, about 6 weeks later I got my plates in the mail scratching my head wondering what she had done. She had special plates made for the car, it was a good one and I said nothing. The plate says COSTLY and I had to agree again, I have five kids ages ranging from 36 to 25 there are four boys and one girl and my daughter is 29. Last time I dynoed the car, after detuning this animal she rolled out with 780rwhp and 820rwtq. And as long as the right foot is on the lite side, the fuel economy isn't really that bad. But when the right foot, gets on the heavy side you can actually watch the needle on the gas gauge move rapidly to the left for some reason. And it too seems to have the same issue as yours, it's the white smoke that bellows from the rear tires to the point where you can't see. Have you found a cure, to your issue with that yet? When you do, PM me and let me know what the cause of it was, Mike. SCT Tuner.:bigthumbsup P.S. That's a photo of it in my avitar, Mike.