kingfish51, yeah, looks like it will only be as part of a spring set, I've found a couple aftermarket suppliers, though the Canadian one pops up a "not in stock, but we can help you find it..." message that isn't exactly encouraging.
The other option might be a low mileage salvage... in which case I could add some slip sleeves between the leaves, since everything would be apart (or nearly so) anyway. Anyone have experience with that? Supposed to smooth things out but I've heard it can reduce spring life.
fordf150farmer, yep, figured it sounded like time to apply the "Don't force it, get a bigger hammer!" maxim
I haven't taken a close look yet (will winter never end?!) but I'm wondering how difficult it would be to fab something? I think the only tricky bit would be getting it attached to the rivet point. The rest looks like simple brake bending or beating metal over an anvil.