@HeatherTe1
So, there are couple of ways you can find this:
You can run a task report,
1) Add filter Task >> Name Contains "Design Lock".
You'll have all the tasks which contains Design Lock
2) Now add new column, switch to text mode and calculate the actual & planned difference in days:
displayname=Planned Duration (Days)
valueexpression=ROUND(DATEDIFF({plannedCompletionDate},{project}.{plannedStartDate}))
valueformat=HTML
another column for actual:
displayname=Actual Duration (Days)
valueexpression=IF(ISBLANK({actualCompletionDate}), ROUND(DATEDIFF($$TODAY,{project}.{actualStartDate}),1), ROUND(DATEDIFF({actualCompletionDate},{project}.{actualStartDate}),1))
valueformat=HTML
It will surely deliver you planned duration & actual duration from starting of the project to design lock completion.
Another way is:
Add filter of successor / predecessor >> Name contains Design Lock
and apply the same filters as above to get the exact days.
Hope this helps! let me know if you have any questions!