The Laker used Central from Jan 4, 1963 to Jan 15, 1965. The train and its connecting Owen-St. Paul train were discontinued after a several-months long fight over the loss of the mail contract. It certainly wasn't done for the benefit of passengers. The deal to use Central was partly to save money, but was mainly valuable for freight and transfer trackage rights that lasted long after the Laker was discontinued. The Laker had been cut back slightly (to Superior from Duluth, and St Paul from Minneapolis) in 1961.
Soo Line's only dual-control GP9, #2555, was often used on the Owen-St Paul connection.
The Soo Line continued to use the B&OCT, as did the Wisconsin Central, connecting with the Belt Railway of Chicago at Kostner Avenue, and going downtown for transfer runs or to switch the Soo Line freighthouse at Roosevelt and Canal just south of Union Station. A better physical connection with the IHB, and later the CN's buy of the EJ&E, moved most traffic off of the line via Forest Park. The Altenheim sub is out of service between the BRC and Western Avenue, and most of the right-of-way and facilities east of Western Avenue have been gone for thirty years or so.
Soo Line's Wisconsin Central used IC's Central after 1899 as a result of losing control of the Chicago & Northern Pacific, returning to Grand Central in 1912. Central was reached via the C&NP/CTT to a connection with the St Charles Air Line in the track tangle just west of the Chicago River.
The B&OCT Altenheim sub was built as the Chicago and Great Western in 1886, merged with the Chicago and Calumet Terminal into the C&NP in 1890, was purchased by the Chicago Terminal Transfer in 1897, and the whole mess folded into the B&OCT in 1910. The Chicago and Great Western was not related to the later Chicago Great Western Railway.
A strange footnote is that the Wisconsin Central was electrified by the Suburban Railroad from a point near today's Washington Blvd on the Forest Park/River Forest boundary to Thatcher Park, a picnic park on the Des Plaines River in River Forest (now part of the Thatcher Woods Forest Preserve) from about 1897 to about 1902, before the tracks were elevated to cross over the C&NW Galena Division. The Randolph Street line of the Suburban Railway to the east in Oak Park was shared with trains of the Lake Street Elevated Railway east of Wisconsin Avenue in Oak Park for part of that period.