In January 1989 the traffic boom was continuing, and so was UP's need for more short term locomotives. In January UP leased 10 ex NW, SP, and BN SD45's from The Oxford Group, parent company of Wisconsin Central Railroad. All ten units had been de-rated from from their as-built 3600 horsepower down to 3200 horsepower. Four were returned in June 1989 and the other 6 were retained until late August or early September 1989.

In January and March 1989 UP leased 11 ex UP and MP SD40's from Oxford. The lease was originally to expire on 15 December 1989, however on December 11th the lease was extended to 31 October 1990. These 11 units had been sold by UP to Wilson during 1988. Wilson resold them to a Wisconsin Central/Oxford Group joint venture, along with 3 other UP and MP SD40's. Prior to their arrival on UP, all were rebuilt by Wilson and painted dark blue with a white "WC" in a red circle on the cab side. The former UP units kept their UP 3000 class number and the former MP units had 1000 added to their MP 3000 class number making them the 4000 class.