Wis. Admin. Code Trans § Trans 254.13
In the event of a breakdown or unavailability of the power unit listed on the application and permit, another power unit may be substituted, provided that the make and vehicle identification number, or license number and state, of the substitute power unit are written on the permit. The issuing authority shall be advised by telephone prior to operating the substitute power unit with the oversize load. Changes in the terms of the permit, other than the identification of the power unit, require a written request and a written amendment to the permit authorizing the change. The driver of a vehicle operating under a permit shall have the amended permit in the driver's possession prior to the movement of the load.
Wis. Admin. Code Department of Transportation § Trans 254.13