I-69 Section 6 will run along existing State Road 37 from Martinsville to Indianapolis.
INDOT is hosting three public meetings in mid-September to show new refinements to the Section 6 plan.
I-69 Ohio River Crossing is holding open houses this month to get feedback on the plans.
INDOT is still on track to take the project over by the end of July.
INDOT will take over construction and maintenance of the road by the end of July.
The first hearing is tonight at Perry Meridian High School on Indianapolis' south side.
The letter says the Indiana Finance Authority, Isolux Corsan, and I-69 Development Partners are negotiating to come up with a "Memorandum of Understanding."
The section of interstate from Bloomington to Martinsville won't be complete until at least October 2017.
The Bloomington company halted work on the project earlier this month because the private developer owed Crider and Crider more than $2.3 million.
Some I-69 sub-contractors walked off the job this week because they haven't been getting paid for their work.