And make sure the front lockouts are in the FREE or unlocked positions too. Just in case.
Not really supposed to run in 4wd with the hubs locked on the pavement anyway, but messing around with an unknown twin-stick setup just gives more room for more unknowns.
In your NV4500, first gear is not really for street use unless your differential gear ratios are mismatched to the tire size. So figuring second gear is your starting gear, shifting to third at 25-30 sounds totally reasonable to me.
A better tell would be to see what gear you need to be in at 55-65.
And yes, these things are often geared towards "utility" and off-road, but that's not always mutually-exclusive to driving on the street. The 5-speed with overdrive changed the dynamics totally.
You might even be using incorrect data to judge your shifts by too. Perhaps with your exhaust and engine noise, you think it's spinning faster than it really is. I know many of us have experienced that, even though we've been around engines all of our lives.
I know my own sounded like it was revving up way to high when I first bought it. But when I installed a tach I found out it was nowhere near where I thought it was. Very surprising to me. And a new exhaust changed that whole feel of revving to a much more normal (for me) level.
Since you can't know what was swapped into the differentials without checking or using a tachometer to verify engine speed vs road speed, there are other things you need to do before deciding to change the gear ratios.
Sounds like you're not going off-roading with your Bronco. That correct? More of a weekend fun-around-town and take the family on an outing now and then? Or do you plan to explore the hinterlands a bit sometime too?
Does your Bronco have a tachometer? If not, and you don't want one cluttering up the dash area, perhaps you can connect one temporarily for this test.
Do you have GPS device you can use to verify the speedometer? You might even be dealing with a completely misleading speedo reading due to the 35" tires. So that has to be verified as well.
If you can compare engine speed at a given verified road speed, you can figure out what gear ratios you have.
If your engine is carbureted, you would really want to be running at maybe 3000 rpm at 70 mph in 4th gear. Overdrive 5th would then take you down to about where that little engine pushing that brick through the air rolling on 35" tires needs to be.
But we can play with that as well.
And if you're more into needing it just how you like it around town vs on the highway, then you can play with gear ratio choices too.
But we need to know what you have now before you can make an informed decision on where to go.
Good luck.
Paul
