[1903USMCUnertl]

Thank you for your post. It is a great car!

Just curious but where did you get the info Chevrolet only had big car short blocks at the time? Just curious as I believe Tonawanda forecasted both production and warranty needs. Not sure why they would over produce an arguably limited use code.

If they only had big car engines available I’d expect to see ID coded engines being installed under warranty in cars during this period., including in Corvettes and I personally have never seen a passenger car coded Corvette warranty engine.

What do verifiable other 68 and 69 Motion SS427 cars have for suffix codes?

I’m not saying it isn’t possible but without some paperwork originating from Baldwin or Motion I’m still leaning to the car being a factory L78 which was upgraded at a later date. Most likely very early ‘70’s.

It is important to remember all of the engine accessories (including essentially all the dated stuff save short block only) is the same between L78/L72. So the dates would already be spot on (provided original to the VIN stuff)

Also since the things on the car which are associated with Motion were all “over the counter” parts.. they could have been added early in the cars life and look completely period correct.

Are there any parts added which have production dates or casting dates? Carb date?

I do think it is telling the valve covers weren’t being used by Motion until later than when the car was built. This logically tells me someone added them at a later date and very well points to the car being upgraded later. Especially given the low mileage and overall original condition of everything else.. .. it would seem to me the original chrome covers would be with the car.

Do you have any period pictures of the car which can date the look? If often found original owners of such unique cars took a few and they help document.

Either way it is a very cool car!

GLWA… I couldn’t let that one go