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.
The Red Wings used Ty Conklin and Joey MacDonald as backups to Howard last season. Howard started 57 games but was injured at various points of the season.
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.