Differential ratio?

Which transmission is in there?

Btrain

I also want to have a more Highway friendly rear end ratio. Would it be cheaper to just put a whole used rear end in then actually changing the gears themselves?

Swapping the third member is very easy, but will probably run you 750 to 1000....and you'll lose the effectiveness of the lower gear set.
What you need is an over drive Trans then, nv3550 or ax15 is an excellent choice for the Early Broncos.
I think I paid $1200 for mine USED , but it was the whole conversion kit.
This allows you to keep the street friendly low gear and keep the highway rpms down.
Here's a kickass gearing/transmission comparison calculator. For best results, Check it out on a laptop or desktop.
http://www.grimmjeeper.com/gears.html
My rig is still under construction, but there are a TON of positive testimonials to the OD trannys.

4spd auto or manual?
If manual , where's the shifter come through the floor?
The NP435 came through way up under the dash. It also has an EXTREMELY low first gear.
I had 33's and 3.73 gears and Low was pretty much unusable on the street.
It rocked offroad though!

The only argument I could make against the ZF is how heavy duty it is and the mods required to make it fit.
For a 2wd cruiser, the NV3550 is a great choice as long as you are not putting a lot of power through it. As I recall, 350-370hp or torque max.
They say it fits in the Bronco like it was made for it.
Hopefully you've been here already?
https://classicbroncos.com/forums/index.php

I want give you a formula to calculate rpm= MPH x reared gear x 336\ tire size hope this will help this on 1:1 final drive

HoosierDaddy

The only argument I could make against the ZF is how heavy duty it is and the mods required to make it fit.
For a 2wd cruiser, the NV3550 is a great choice as long as you are not putting a lot of power through it. As I recall, 350-370hp or torque max.
They say it fits in the Bronco like it was made for it.
Hopefully you've been here already?
https://classicbroncos.com/forums/index.php

ZF is the transmition I'm running with NP transfer case, I had to put a 4" body lift and get a new transmition tunnel from Toms bronco removing the 435 NP change the bronco with very positive result. I'm running 4.11 at 65 mph I'm running 1750 rpm

he'd do well w/the World Class T5. Nice combo w/the 5L bent8. I can see 2.73 - 3.55 rear gear?
Lower it a bit (1 - 3 inches) on some 14 or 15 inch 28 - 31 pizza cutters? Get some MPGs w/that...
Put a roof rack on to up the carring capacity? (enclosed box or open rack) bed is so small...

What holds up the inner ends of his axel up frnt if his chunk is empty?