I bought it as a crate long block back when Ford was dumping the last of the 5.0 motors. About 4 years ago. It was odd, you could see that they'd been fully assembled and then stripped again. Ford sold all the intake/electrical harness assemblies separately, but unlike the long blocks they all went to dismantlers and bulk sellers. I got one of those setups, which included upper/lower intake, throttle body, engine wiring harness, fuel rail and a bunch of sensors. I had to find my own front dress. At the time junkyard Explorer 5.0's were still pretty rare so I went with the Mustang serpentine stuff. Rather than trying to make the OBD-II stuff work (and I didn't have all the parts anyway) I trashed the wiring harness and some of the sensors, then using an FRPP harness and sensor kits plus other bits I scrounged, I converted it to 89-93 style Mustang 5.0 engine control. No big deal to do. I also had to toss the fuel injectors. For (I believe) the last few years of the Explorer 5.0 Ford used an oddball 17 lb/hr injector with a non standard electrical connector. They aren't compatible with EEC-IV so I bought a set of 19 lb/hr injectors as found on all the 5.0 HO motors, with the orange tops.
In all it's a great swap. There's an issue with spark plug interference on the Explorer 5.0 motors with gt-40p heads, but the first couple of years had straight gt-40 heads so any header will work. I have the former and modified my Wild Horses shorties to fit. Do a search here on Explorer and gt-40p. It's been covered in lots of threads. Either of those heads and the intake are much better flowing than the Mustang motors. The Explorer cam sucks. I swapped mine for a Crane stick. Several tuners I've spoken with around the country say that an Explorer 5.0 with a little port matching, cam change and decent exhaust can be tweaked to the far side of 280HP at the crankshaft. One guy was confident of 300. Of course you won't have the torque of a 351W, but it's no slouch. I have no idea what mine produces. It's a LOT more than the tired stock 302 it replaced.
If anyone is seriously considering the swap, I say go for it. I'm seeing good Explorer 5.0s go for less than $800 complete. If htere's interest I'll do a writeup on everything I did to complete my Explorer 5.0 swap (it won't be a how-to on EFI though- that's covered well in other sources) and maybe Jon will post it.