Unless it is guarantee to work, I would not. As I said, 4 out the 5 modules I got were bad.
As well, if there is a secondary issue, such as wiring, that killed the other one, as opposed to it up and died outright, when smac puts another one in, new or used, it might instantly fail, making it appear to be yet another bad unit, even if it's not - self-fulfilling prophecy and all that. I'd want to look inside the old one first, as sam suggests.
smac:
But, something has to be tried, so... I'd go with the one that, as falcon says, is guaranteed to work, and has the best warranty. Keep in mind that many electronic items come with restricted warrantees, so if it blows and you take it back, know where you stand ahead of time, just don't use those words.
As for the shop's tester saying 'permanent failure', I'd wonder if it is compatible with an early SC (not all ABS testers are), and threw that error simply because it didn't know what else to do. Did the shop staff that owns an SC say they've used the tester on an early model with positive results?
Yet another reason to have a Ford dealer take a shot at it (call first and ask specifically), as if anyone would have the right ABS tester they would, even tho I'd do anything to keep mine out of their hands
Don't let them do the work, just pay them to test the ABS system electrics.