Essentially, it's STUPID tight between the frame rails for the 5.0, particularly for the exhaust.
The starter is only a bit behind the right engine mounting plate and the steering shaft is seriously in the way on the left.
So, the right exhaust needs to exit above the starter, almost straight towards the back of the vehicle.
On the left, Ford crunched in the dino fluid sump to allow the left exhaust drop straight down, very very tightly up against the block/dino fluid sump.
Yea, the 5.0 is in there tight.
So, to redirect back to the original question, the only other exhaust option:
Long out of the the Ford parts system but they still pop up used are a set of Ford Racing Parts exhaust headers for the 5.0 Explorer. Read of a guy that found a NOS set at his local Ford dealer a year ago or so.
Not exactly unicorn horns, but quite uncommon.
The Torque Monsters do show up used with some regularity.
Used, the TM's and FRP's would take time and luck, but they are out there if OBX cannot reestablish availability.