Hot Rods Back window ID

I am trying to figure out what the back window came out of. It was going to be used for a 53 Chevy chop top. It measures out to be 18x40 across. Thanks

 

later model VW beetle?

 

Do the steel sides really curve around as much as it seems in the pic ? Probably a small stationwagon tailgate.

 

Actually they are pretty straight, it was going to be used for a 54 chevy chop top rear window.

 

I was thinking maybe it was cut from a '49 Packard...

 

Reveal on it suggests VW bug like 68-up. Is there any ID markings on the glass?