OK I'm a newbie to the 4.0 but I am trying to evaluate the gearing
I will need.
So far with 33" tires I like the response I am getting with 3.73 gears.
I may gear to 4.10 when I build up the dana 44 I hope to then run 35" tires.
On a side note looks like the front wheel driving will take a tole on my old universals joints. I have one squealing now. Don't know why they only have 160,000 miles on them. 
You are fine with 33's and 3.73 gearing. You should only be a few hundred rpm's under stock. I wouldn't bother going to 4.10s from 3.73s. 4.10's would put you nearer the stock rpm range but if you are going to 35's you will need 4.27's or 4.56's to get back to stock rpm range. If you want to change gears go to one of these instead. If you have an overdrive, go with the 4.56.
The one big thing you have to consider is the 44 carrier break. If you want to lock the 44 then I would def. go with gears higher than 3.73's. This way when you go to 35's you wont' have to worry about a new carrier
Joe,
If you have 5 speed, regear to 4.88. Remember bigger tires and higher lift need more power. It is more than just RPM consideration. Been there ;).
Later,
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