Full-time 4wd transmission with locking center diff questions

With the driving I've been doing lately, I've been considering switching to a full-time 4wd with locking center diff. I've been doing a LOT (sometimes 50 miles/day, 5 days a week) of gravel and dirt roads, too loose for 2wd, too solid for 4wd. I've been searching the forums for information about these transmissions, and the posts I've found mostly seem to be from people who have never seen one, as most of the information is directly contradictory... so I'm hoping to get some solid answers.

What I want: 5spd full-time 4wd with locking center diff, 1.59:1 low range, 3.9:1 final, widest 1st-5th ratio possible. I'm in the US.

Some posts say only the RX had full-time with locking center diff, some say also the XT6, while others say any ea82 turbo might have one. How to identify them is utterly unclear, either from looking at the transmission or at the interior of the vehicle, with no one apparently ever having actually seen one or otherwise giving a useful description. Some posts say they only came with 3.7 final, others say half of them are 3.9. Most say they have a poor (1.19, 1.2, etc) low range, but some say the 1.59 is a direct swap, some day it's not, some say you need au-only gears, and one even says 4spd parts fit, while I'm rather sure they do not. Some posts say that if you get a 3.7 you can swap the 3.9 pinion from an EJ box in, others say you can't, while some say you need XT(6?) parts. Some say it's a mechanical shifter, others say it's electric. el_freddo has a post saying nothing swaps without welding, but his posts are specific to a dual-range EJ tranny that's not available in the US, while I'd be using EA82 parts. Some posts say I'd need three transmissions, an RX, an XT6, and a non-turbo dual range.

My current 5spd dual-range is in need of a rebuild (multiple bad bearings, input shaft wobbles an eighth inch, something clunks like a rod knock when in neutral, 5th->R lockout sometimes requires going all the way to the left then back to get to 4th, selector sometimes jams, synchros aren't the greatest, leaks from every single seal top and bottom and back and front...), so I wouldn't feel bad using it as a parts donor for the low range gears.

I've tried doing a couple searches, and couldn't find anything available that looked like a full-time box. But, I don't know. car-part.com lists the full-time separately and says there's two available, but I think it's just lumping all ea82 transmissions together.

So... What parts do I actually need? How do I identify them, either looking at the transmission or at the car it's in? Are they even available at all?

Edited 3 hours ago3 hr by bushytails