I am looking for a site where I can find equivalent in SMD from normal through hole components.

I am actually looking for a SMD transistor similar to a TIP41

 

I've always liked the search feature of the Digikey.com site. You start searching by a general category (say "transistor") and can pick parameters that match your needs till you get a small set of parts.

Since package type is one of the search criteria, this should be a quick hunt. You can even pick "Mounting Type: Surface mount" to just eliminate all the leaded devices.

 

I think the Diodes Inc DSS60601MZ4-13 is about the best you'll be able to find. It has the same basic specs (60V, 6A) as the TIP 41, and there aren't many surface-mount transistors that will carry that current. However, if you're using it in a linear mode, heat removal would be a serious problem.