The original purchase order for the Electra dated March 20 and signed by Amelia on March 23, 1936 (attached) specifies:
"Gasoline capacity to provide range of 4500 miles in accordance with our letters dated 2/21/36 and 3/5/36."
This strikes me as curious. On what basis is Lockheed guaranteeing a range of 4,500 miles?
Report 487 "Range Study of Lockheed Bimotor Airplane" was not published until June 4 and the test flights upon which the report is based seem to have been flown May 18-20, 1936. Unfortunately, we don't have letters mentioned in the purchase order.
Why 4,500 miles? Officially Earhart has not yet said anything about a world flight, even to Purdue, but 4,500 miles sounds like the range she'd need for her original plan to fly solo from Hawaii to Tokyo.