I used to use **broken link removed** but they have started charging to view the datasheet. It does tell you which company makes them, once you've found this out you can usually get the datasheet from the manufacturers website. For more common components I use www.rswww.com
Some large companies write their own transistor specs, so the transistors have a private number that you won't find anywhere. You can ask the manufacturer for a replacement number, but they will probably just tell you to send the unit to a repair depot.