Can any one ID this flywheel application

[Jerry M.]

I have a flywheel with the # 3988999N on the back and it's not in any of my parts books. Trying to ID it's application to see if it will fit a 66 300 hp
powerglide conversion. Thanks Jerry

[Mike Cobine]

Re: Can any one ID this flywheel application

Does it fit? The easiest way is to compare to your old one. If you don't have an old one, then see if it will fit the mounting holes to the torque convertor and the bolt pattern on your crank. And check that it matches where the starter drive will engage.

Now there may be some differences in how much torque it will handle or if the holes are stamped the same places, but if all you want is functionality, then you don't need to worry numbers but if the flexplate will bolt to the torque convertor, the crank, and engage the starter drive.

[Clem Z.]

Re: Can any one ID this flywheel application

since the 66 SBC uses internal balance and if there are no extra metal weigth on it to make it a extrenal balance it should work.

[G B.]

Rare piece

That is one neat flywheel. I'll bet it's a 14" diameter, very heavy flywheel with bolt holes for a 10.5" clutch only. Am I right?

In 1962 Chevrolet built six Pilot Line flat-bed trucks with Z11 (Mystery) 427 engines to haul the Grand Sport Corvettes. I believe that was the only factory application for the nodular iron 3988999N flywheel casting.

I've also heard that some of these special tow vehicles were actually converted into ordinary looking dump trucks AND THEN SOLD TO THE PUBLIC in late 1963. They're out there somewhere! Please don't waste this flywheel on a '66 Corvette!

[Robert W.]

Re: Rare piece

Jerry- I know a fellow here in South Carolina who swears he has one of those prototype 427 motor haulers and you are correct, it was converted to a dump truck in 64. I would believe him but he is also the fellow who when a gentleman whom he worked with said his wife had a hysterectomy and bragged she returned to work in three weeks he said that was nothing he had one as day surgery and returned to work the next day.