After replacing the rear differential, the vehicle is experiencing multiple issues?

Mine is 4x4 XLT it come factory with 8.8 3.55 or 8.8 3.73. I'm 2 wheel drive version which according to Ford is interchangeable I pulled the tag off original rear differential myself and I counted the teeth on both I tried rebuilding original without a runout gauge and none of these were an issue until I swapped rear end according to live data on scanner every speed sensor are reading correct speed but the it says no fault in the speed sensors but under speedometer it says I'm doing 100 mph how is it possible that sensors are reading correct speed but the speedometer isn't but both systems being monitored at the same time I will get someone to spin wheel like you said cause at this point I feel it is something stupid and it is worth a shot thank you it'll be tomorrow morning but ill post what I find out.

Correct this all started when I swapped it with an 02 explorer 8.8 3.55 differential and just too be sure I went and swapped that rear end out and pulled one out of an 03 like mine but same gear ratio and still the same problem but before that I didn't have a single abs light on or nothing and every symptom I'm having says it's the rear speed sensor the only difference is my O/D still works where everyone says their O/D light blinks mine doesn't.

Yes, I can do that and afterwards I'll scan again if it gives code and post a pic of the results for you to look at. I just hope I can get it figured out soon because this is my daily driver. Thanks again for your help.

I unplugged the sensor and didn't change anything. It turned my ABS light on, and the pics are the codes it threw after I drove it and I had cleared all codes before driving last night but today the ABS light is off, and I still have the check engine light. But I've noticed the past few times I was running live diagnostic with scanner and my entire cluster would quit working except for warning lights no gauge would function and my scanner said no connection and it would be retrying and cluster would function again, and scanner reconnects after a min or two and never does it when unplugged from the obd2 connector. It's happened every time the past week that's why I think it's something really stupid I'm missing somewhere ground wire or short that's causing the issue vs mechanical failure, but the only wiring touched changing the rear differential was the sensor plug and I even wired a new pigtail in just to eliminate that possibility.

Now I'm only showing 1 code which is heated oxygen sensor bank 2 and system readiness not completed. None of the other codes are showing now. If I remove the gem, I have to have the module flashed with the old ones configured right? This is what the scanner said yesterday, and I got to looking at the engine and noticed the speed control cable was off the outside nipple beside the throttle cable and I reattached it and now it's not giving the code anymore today.

It didn't fix the main issue, it just narrowed down some of the codes I was getting. I'm going to check a few more spots of wiring and if I find nothing then I'm going to do like you said and replace the gem.

Is there any way I can test the GEM? Because I don't want to go through all the hassle and have to spend a few hundred bucks just to be in the same boat I'm in now.