Digi-Key rocks! Ordered MOSFETs Sunday night, they will arrive today, via USPS first class mail, cheapest shipping alternative: $4.95. So, about $10 for 3 MOSFETs. Time to fire up the soldering station - I have a pretty good soldering/desoldering rig, with vacuum desoldering, etc.
The plan is to remove the old one and test it, just to confirm; there's a technique for testing MOSFETs with a DMM. Then install a new one. Won't take long.
Meanwhile, I have the MC-614 that
@Scott T-Bird so generously sent me. That could be a quick swap, as both use the standard Ford plug, and that's all the wires you really need for this. However, if I go with the 614 long term I will locate it outside the engine compartment, which will require re-routing the harness. The existing harness is still full-length, it was just bundled-up with cable ties, so not so tough.