I'd like to know, what, who and when.
American?
Customised 1939 Ford Mercury?
Yes, it's a customised Ford, from USA.
Is this a 1940 Ford customized by Gil Martin in 1950-1952?
This is not a Gil Martin's job.
Up.
Built by Arthur Lellis?
Not Arthur Lellis.
This looks just like Chuck Manning's 1939 Ford Coupe.
Except that this one is an open top , with a different bumper.
So: a Chuck Manning creation?
Not a Chuck Manning's job.
A fella named Dean Cosey from Indianapolis made this custom 1939 Ford. It had a removable hardtop that could be stored in the boot apparently, a 185 hp engine and a set of 1937 Cord instruments in the dashboard. unfortunately I don't know when the conversion was made, but definitely in the 40s.
Yes!!! You got it...well done.