Mystery Thunderbird

[66QBird]

Wondering if someone can help me out with the reading of the VIN. I have a 66 Thunderbird landau (I thought was a ) 428 "Q" code. The code on the door reads Q as does the VIN on the title. The breather cover says 428. I just noticed, however, the codes stamped above the radiator and in front of the windshield under the hood read all the same numbers as the VIN on the title but with a Z where there is a Q in the VIN. So I'm wondering, is this a correct 428? Or has someone done a switcho-chango and trying to pull this off as a 428? Frankly, I couldn't tell if this is a 390 or 428 engine by looking at it so am at a loss. Any advice would be helpful. Thanks.

[Harley Eaton]

428 or not? The Original Factory Specifications (the OFS) states this: The external visual clues for a 428 include the external balancing weight mounted against the harmonic dampener pulley, an externally balanced transmission flexplate, and the engine identification mark "EHJ" stamped on the machined boss on the driver's side of the block.
of course, you know the VIN should be "Q". I would trust the stamp on the radiator and cowl over the title. (All 428's used the C-6 transmission.)

[Frat_man-du]

I agree with Harley. I have seen VIN tags changed (several companies will produce any variation of the tag as long as you can show ownership) for M and Q Engine code as well as 76 vs 63 body codes. The stamps on the body are hard to change, but not all together impossible, just unlikely. Now it is entirely possible the original customer changed his mind after the stamping and before the VIN tag was applied at the factory. Best thing to look for is any of the ROT sheets (check the backs or the back seat for one of these sheets and look for the Q in the VIN or if you have the Gate release it should help to. Not that this is definitive by any means one of my '65 convertibles has no VIN tag from the factory, the gate release shows in a hand written note that there was a production substitution, they ran out of black leather and vinyl was substituted and a replacement patent plate was mailed to the selling dealer - the order and org tag clearly shows black leather interior but since the car was built the only thing to prove it came from the factory with vinyl was the gate release with this hand written note. The org tag was removed but the new one was never installed…lucky me….

[66QBird]

Thanks for the responses. Yea, I have to dig around for the ROT sheet> I looked under rear seat, but not on seat backs.

[Frat_man-du]

I had three one under the pass seat, one on the rear seat back and one taped to the bottom of my convertible package tray. I have even seen one under the carpet. Good hunting!!!