Safari is 4.2 inline 6

Current Patrol is 3.0 inline 4

Ford diesels are not available for their light duty trucks. Yes, the Expedition is part of their 'light duty' line up.

AFAIK, F350 and E350 up ang may diesel option. The Expedition is based on the light duty F150 platform.

The diesel E series vans were never popular here. They were too expensive and the heavy duty underpinnings (for cargo/towing) gives it a very punishing ride.