1065 401-k contribution by extended due date

1065 401-k contribution by extended due date:

Can we file a 7004 before 3-15, file the tax return by 3-15 and still have until 9-15 (the extended due date) to make the 401-k matching or does the contribution have to be made the earlier of the extended due date or date filed?

Extended due date. Can file earlier as long as 7004 in place.

Thanks Taxmaster for the quick response. Thank you.