No problem with the amp & sub
You will not have any problems with the amplifier or subwoofer amp in this swap.
In the Ford Expedition, the same head unit can be used with "Premium Sound" and "Audiophile Sound" (JBL). For most model years, Expeditions had Premium Sound standard on Base models, and "Audiophile" Sound (with SW) standard on EB.
Unfortunately, the bean counters got in there, and didn't want to pay the premiums for "JBL" licensing, so instead of "Premium Sound" and "Ford/JBL", we have "Premium Sound" and "PREMIUM Premium Sound" (sorry, it never made sense to me, either, but we couldn't get it fixed). The system in the EB is basically a Ford/JBL system without the logos (and includes a SW).
The head unit sends a line-level signal to a remote amp. There are two diiferent amps - a 4 channel for PS, and a 5 channel (4 EQ'd + a line-out for the SW amp) for JBL. So the same head unit will work in either a Premium Sound or a Ford/JBL type system.
This is different from a 1995-1997 Explorer, which uses a unique "distributed architecture" in it's Ford/JBL system. These units, using an -18C852- HU, are very complicated, and cannot be easily upgraded.
Regards,
Jeff