The 5.4 and 3.5 both have the same 9,200 max rating with HD tow. On either truck verify that it has the round Ford 7-pin connector on the receiver. Both would also have the built in trailer brake controller if they have HD tow. Both engines have known issues of timing chain components but are overall solid short blocks. EPAS steering on 15-17 saves some gas, but most F-150 owners report does not last as long as the hydraulic setup on the modular engines. The hydraulic rack usually lasts the life of the vehicle, the epas seems to average 100-150k. My aunt owns an 08, 14, and 17 and likes all of them, when I’m at her house there are 4 Expeditions. It’s like an expy party.