Nice looking truck. I'd like to add some things to think about though. The A4LD is a great trans on and off road while it lasts. With the high miles you have on yours I would be not want to go with larger tires than stock until I something is done with the trans. As was said it may have an aux. trans cooler. Check your radiator. On the drivers side engine facing part of the radiator below the radiator cap are your trans lines. Follow them back to see if you already have an aux. cooler. It will be a small radiator looking cooler. If you have one no need to install another now. I would not do a complete trans flush. Just drop the trans pan and clean and install a new filter(screen). Buy a good service and repair book for the proper way and torque sequence. When you buy the new gasket, filter, and fluid locate a retailer who sells BG products. This is great stuff. I had a A4LD in my 89 Bronco II and it let go on Hotel Rock Trail in Utah. I cooled in down and refilled with fluid but it would not pull on a incline. Drove up to Moab (about 3 hours) and stayed in a campground. The next morning it would not back up until it warmed up for about 10 minutes. Went to a shop that sold BG and put a can in and it worked great. Drove it home to Kansas over the passes in Colorado. Do not buy the cheap trans fixes in a bottle. My friend that recommended BG rebuilt trans for a living and said the have brake fluid in them. They can lock a tranny up so tight they cannot be disassembled. old transmissions use varnish build up on worn parts to work. A tranny flush could clean enough of that varnish away to make it stop working. You might consider either installing or having a trans temp gauge installed. That way you can monitor your temps. If you are good at wiring a big red light would be great to tell you when to pull over and cool things down while idling. Even with all this I would stay with stock tire size. Taller tires without changing gear ratio is like pulling a trailer all the time. Hard on the trans and cost more in fuel. This is why many used car dealers will remove a hitch from vehicles before putting them on the lot for sale.
You did not say if you are planning to do any off roading or much other driving in this current condition. Or how long before you are planning your Nevada Expeditions. The above with other service of engine, cooling, brakes and drive line would be good for local mild off road trips with stock aggressive tires. A bit about the 35 TTB independent axle. First in stock form and mild wheeling the auto lock outs are fine. Just service and replace worn parts. They use a different locking method than the manual lock outs and do not require 150lbs. of torque. Final torque according to my Chiltons is 16 inch pounds. If and when you do decide to change to manual lock outs get the Warn heavy duty lock outs made for the rear dana 35. These are a lot heavier and I run them. Do not buy the Warn conversion kit. Go to a Dana Spicer dealer and buy the stock 2 large nuts and lock ring for each side. Saves a bunch of money that way and you get the same parts. The 35 does have some things that need to be addressed with proper service. First is that the design placed the front wheel bearings very close together. This does not give them the strength of others with wider spacing. So they need to be replaced more often. Another related issue is spindle removal. Please stay away from advice to hammer or pry off the spindle. There is a socket that can be purchased like this one
https://www.amazon.com/dp/B004KEHECY/?tag=serious-20. You will need a slide hammer but many auto parts stores will let you use one when you buy your service parts from them. Behind the spindle are seals that keep water and dirt out of the lock outs and bearings. I would include this to the list of service for you Explorer. And don't forget driveshafts and transfer case.
If you are not going to do any wheeling local or in Nevada until you have it the way you want it you can still start with all the things listed. Then transmission is first on the list. You can buy a pedal assy. and switch to a M5OD. If you do try to get one from a 2.9 as 1st gear is lower and you will love it off road. Of course if you can find a really good A4LD specialist out in Cali that is an option also but I would have an over size trans cooler and the temp gauge/light. The thing with an auto trans is heat. Std. trans don't need to be cooled and auto's do. That heat goes into the engine compartment and radiator. But for off road an auto is awesome. Much easier to work 2 pedals with 2 feet than 3 pedals. Then you need to decide on tire size an lift. You need to check what gear ratios you have now. If you have a high (numerically low) ratio then you can look for used parts with low (numerically high) ratio's and figure how tall of a tire you will need and how much lift. Car-Part has been good for me in the past. And you can think about if you want to add a lunch box locker or not.
I run 33's on my 94 Sport with 3.73 gears and a mild lift. But I have a lot of other mods. C-4 auto, Stubler 2nd low range box, and lockers front and back and I can do most difficult trails in Colorado, Utah, Nevada, and Arizona. I drive mine around Kansas with 31x10.5's but put it on a trailer with 33x 10.5's to go out west. Mine is not near as nice as yours.
If you have any questions please ask. You can PM or e-mail me. I can even get you my phone number. Take care and good luck.
