How the P-8 and E-7 share an airframe family

What is the connection between the P-8 and the Boeing 737?

The P-8 maritime-patrol aircraft and E-7 Wedgetail use related Boeing airframes with logistical commonality; the exact designation is recalled hesitantly.

The P-8 is a maritime-patrol aircraft with anti-submarine, intelligence and anti-surface roles. The E-7 Wedgetail provides airborne warning and control. The exact Boeing designation is momentarily uncertain, but the two aircraft are described as related models with enough logistical commonality to simplify support.