Penn Central in Michigan

Does anyone know when the old Penn Central line between Lansing and Owosso Michigan was abandoned?

The PC System Trustees map in the 8-72 Trains shows they wanted to keep it. The map in the 4-73 Trains shows they wanted to abandon it.
It was probably among the 6063 miles that Conrail did not have to buy.

Abandoned 4/1/76. A small stretch was kept in place from North Lansing to just east (north) of Wood Street to store auto parts cars, but this too was removed about 1980.