The '96-early '97 Explorers/Mountaineers had the GT-40 heads, same as the Cobra Mustangs, and are dirrect bolt-ons. The intakes from these engines have internal egr passages like the Mustang intakes.

In mid '97 Ford switched to the GT-40P heads. They have angled spark plugs and don't work with most aftermarket headers made for the earlier heads. The intakes from these engines use an external egr tube and have no passages.

All Explorers/Mountaineers use a 65mm throttlebody, an upgrade from the stock Mustang unit.

Hope this helps.

Greg