Dad has the 3.73s in his (ZR2). I've seen everything from 3.08s to 4.11s. There may be even a wider range than that.
That must be a fairly tall overdrive 5th, to get 2400 @ 55 with 4.11s. I've seen 1:1 4-speeds with shorter tires running right at 3 grand @ 55...
...not conducive to good fuel mileage!
Here is a place that you could look around and maybe find something...