Jose, that second is sounding pretty good, especially with the price drops, Check it as you would the first one. Pointers on the transmission ----- Put it into gear within a few seconds of startup. Forward and reverse, Make sure theres no excessive lag before it goes into gear. Watch the first to second shift, feel listen and watch the tach, make sure it shifts normally and not very early or very very late. Get up to highway speed and make sure it drops rpms, etc. Hit the overdrive off button and see if it raises the rpms or if the O/D off light starts flashing. Do a quick almost panic stop when you can and immediately take back off. Make sure it stays in gear, doesnt clunk as your stopping or as you go to take off again. Those are the biggest pointers I can give you on these transmissions.
IF you do get any of those to show a problem, dont throw it out just yet. Most of those could be that its just low on fluid. As another poster mentioned, there is no dipstick, you have to check it through the plug on the bottom. Really a lot easier than it sounds. Lots of threads on it and I can pm you if you still need help. (I would check the fluid after purchase regaurdless of symptoms that may or may not appear) This one does sound like a lot better choice so far.
The first one still doesn't sound quite right after you finding the pictures of the damage. Like the other poster, I still don't see enough to total it, Maybe they ran over whatever they hit and tore up stuff underneath? Easily a possibility which could result in enough to total it. Still could have been fixed properly, if this second one doesn't pan out, Maybe keep the first on your list to check into.
As far as the 4 wheel drive, My Explorer was 2 wheel, Drove it in snow and ice without much problem, some mud. No replacement for 4 wheel but it got me where I needed to go. My Mounty, the previous owner took the front axle out when it started grinding instead of fixing it, so its not AWD right now. I also had it in some nasty ice and snow with crappy tires and got around pretty well. Deep snow or playing in serious mud, I wouldn't necessarily do much of it or do it purposely. Thats gonna be up to you. I've had a few other 4wd and I prefer it, so the mounty will get the awd back in order as soon as funds allow. We also tend to get nasty winters here and I occasionally hunt mud holes and we have some real dirt roads here.... Wishing you the best on your purchase and We're here for advice and whatever help we can offer. Used transmissions around here run about 600+. A rebuilt will probably set you back $2500, new around $3600. Depending on where you go and what all you have done.
That being said, Just write down or try to remember what I said about what to check on the trans, drive it like I stated to drive the other one, listen and feel the truck as much as possible. Price is excellent even if there are minor issues.
Last thing, Listen for rear end whine, Most of these have it but if it sounds like an airplane, then it may need a rear diff, Some whine is considered normal. If your not sure if its the diff, go somewhere where you can get fast enough to hear it and swerve some, If it goes away or gets quieter swerving one way, its a wheel bearing, if not and it stays constant with speed and changes pitch letting off the gas then its the diff. All depends on how loud or if you can feel anything associated with the noise. If I was close Id go with ya and check it out but thats a little bit of a hop for me based off the craigslist ad you posted.
In closing, every car line is going to have a forum or B!tch site complaining about car problems/common problems. Thats why we have our forums to help people out with those and so people can find out how bad or not bad a problem may actually be. Our trucks have inherited flaws but most are easily taken care of thanks to all the info and help here. Good for you though using the links you found to get a better deal. Hope it turns out to be a good one for ya. Keep us posted and hope to see you making new posts about the new ride.