I got a 2001 Jeep Cherokee spare from one I parted out, I've tried it and it fit's fine, 5x4.5" Should fit over the 4x4 hub too, one of the rims from the regular set of Cherokee wheels/tires is my spare currently (215/75R15 in fact!), as my original spare wouldn't fit over the hub of the Explorer 8.8"
Should have zero trouble finding them in a junkyard.
To all of you hating on doughnut spares, they are a perfectly reasonable, space saving, lightweight solution.
I toss my aforementioned doughnut spare in the truck when I use my trailers (also 5x4.5")