I have a 2011 2wd and have been thinking of going 4wd and have a few questions for those that might know.

1) Is there any difference in there frames other than the mounting brackets?

2) Are the upper and lower control arm brackets in the same place on both frames?

Trying to figure out how hard it would be to convert it to 4wd. It looks like the rear trans crossmember is in the same place on both but is just different for the 2 styles of suspension. What I'd like to do is mount an IFS 4wd suspension and axle in the 2wd and go with a manual transfer case eliminating all the vacuum and electronics that's used in the later models, and use manual hubs.

 

Yes, front 1/2 of frame is different, couple of difference but main one is that they used Boxed frame rails in the front for 4WD

4x4 is built from frame out, so not even Ford changes 2WD to 4WD, it starts with the frame, it was not an "option" added after the fact

You can see differences in front suspension here: The Ford Ranger Front Suspension

You can do it of course, but with a 2011 2WD I would just sell it and buy a ready made 4x4 and fix it up the way you want, it would probably cost less.
Or buy a Rolled or otherwise damaged 4WD and swap your body over to it

 

I guess I'll have to look at and do some measuring on a 4x4 to see what I would have to do. Buying an existing 4x4 isn't what I want, I want a simple manually operated 4wd system not the electronic system. Maybe I can adapt a TJ axle into it, but steering is going to be a pain.

 

2001 and up Rangers had Live Axle 4WD so no hubs to lock or unlock, so all you really need is a manual transfer case to change it over.

And you need that regardless if you change over or if you buy a 4x4

I think the Ranger FX4 Level IIs had manual transfer cases and 4.0l engines up to 2003, in 2004 I think they dropped manual transfer cases.
While you can just buy a manual transfer case the shift linkage can be hard to come by

You also need the transmission from a 4.0l 4x4 so transfer case can be used, if you stay with automatic then you need the 5R55E from a 1998 to 2012 4.0l 4x4
Manual trans could be from 1990-2012 4.0l 4x4

Yes, people have used different axles up front, just have to make sure differential is in correct position for transfer case front drive shaft, you can't "flip them over"