Jimmy Howard will have a new backup in Detroit.
Gustavsson came to Toronto as a heralded unrestricted free agent out of Sweden in 2009. He went 39-45-15 in 107 appearances over three seasons. Gustavsson posted a 2.98 goals-against average and .900 save percentage.
The Leafs traded Gustavsson's negotiating rights to Winnipeg last weekend for a conditional seventh-round pick in the 2013 NHL Draft, but the sides never struck a deal.
It will be interesting if Gustavsson for some reason gets the start in the 2012 NHL Winter Classic at Michigan Stadium. The Red Wings' opponent is the Maple Leafs.