We were able to get some of the data that we need using a "Ticket Tasks" report in the Analysis module.
Here are the fields that we use:
ID, Title, Ticket, Responsibility, Created, Completed.
Then we have to take this into Excel or SQL Server to calculate the elapsed time between the Created & Completed dates and develop these reports.
Would be nice to have an "elapsed time" field added to the Ticket Tasks reporting built into TD. (BTW there is a "Duration (Work Days)" field, but this only calculates the time elapsed for the (parent) ticket, not the ticket task)