I never saw this in person but saw pictures of it. IIRC these are the
characteristics:

1. "old" - I'd say from the 1930's to early 1950's.
2. monoplane
3. prop - can't even remember if it was single or multi
4. I'm guessing about twice the size of a DC3
5. closed cabin (I'm guessing it had a cabin) but definitely an open
cockpit. This was the most distinctive aspect of the a/c. Looked like
two guys in front of an 18 wheeler but the cockpit was open.
6. I think it was based north of San Francisco and might have attempted
to cross the Atlantic but had to stop on the east coast of the US due to
a mechanical.

any ideas?

Thanks in advance.

Gerald Sylvester