[jocko]

4.10 with a 2004R with 265/75/16 (31.7")tires =
1893 rpm @ 65
2184 rpm @ 75

3.73 with a 2004R with 265/75/16 (31.7") tires =
1722 rpm @ 65
1987 rpm @ 75

so about a 150-200 rpm drop at speed. Not a big deal. And probably not worth the cost, that's why if I do it, it will be waaaaay down the road and after I hit the lotto.
2004R is the best bang for the buck and pretty much eliminates the need for the 3.73. Just the 2004R alone drops 65 mph rpm by almost 1000 rpm/75 mph rpm by about 1100.
Just the 3.73 alone would help a bit, but not enough to warrant the cost in my mind - if wanting most bang for the buck, 2004R is the way to go for highway cruising (or a 700R4 for folks that like it, slightly (unnoticeable) higher rpm in o/d than a 2004R).
BUT, the "ideal" setup would be a 3.73 with the 2004R in my book - better 1st gear final drive ratio than the 2004R/4.10 combo. But I can live with that. I'm just glad it's not pukin trans fluid all over my garage anymore.

Compared to the current stock 4.10/TH350 setup, both are a huge improvement...
4.10 with a TH350 with 265/75/16 (31.7") tires =
2825 rpm @ 65
3259 rpm @ 75