I did a search and ended up on Quadratec's chart. I looked at what Flivver250 probably needs and it costs about $30 while the others I checked are $40. Hmmm....
Anyway, I've never worried too much about the speedo being accurate even way before anything electronic could tell me the actual speed.
Right after I got new tires I checked some GPS on my wife's phone and my speedometer was within 1 MPH of it. I've also been past a couple of radar signs that are also within 1 MPH FWIW, my TJ is stock and the tires are just a hair bigger than the originals.