While performing a migration from SQL Server 2000 to SQL Server 2014 (wow what a big jump), I needed to find all stored procedures that made a call to an extended stored procedure that was being replaced with functionality that is baked into more recent versions.
So what to do? Stack Overflow had a few good suggestions, but Red Gate’s SQL Search came out on top. If you have the ability to install it (hard to do for some clients) then it’s a great option.