exactly what my next recommendation was going to be. Take the inspection plate off, sans the broomstick. I would use a dead blow hammer. And just give it a few shots. If not then I would resort to a crowbar.

 

Ok you took the donor tbox apart with the front driveshaft flange and
gears still attached to the case right? It was not attached to a transmission.
Have you removed the front flange and output case from the gearset you are trying to remove?
If you haven't, It may be hanging up on the trans. It's been a long time since Ive had these tboxes apart I vaguely rememer one that was a little difficult.
I have to run over to the shop this morning.
Give me a call and I'll try to walk you through this
732 Three three seven 0 seven 8 six. i'll be there around 9

 

Silly question but I'm not there and don't see it.. you did remove the hi lo lock solenoid and neutral switch right?
The other option you have is to pull the rear output housing.
the front diff shaft splines into the output shaft. The output shaft goes thru to the
tbox to the center diff.
This should give the final drive gears enough room to get past the intermediate gears.
It's only a driveshaft, ebrake and 6 locktited bolts and a hammer away.
Also low range is where you want to be.

 

I got the front output out! I had to take off the rear drum brake and the rear output. Took another 45min and about 8 bolts. Top right bolt was a super bitch, but it slowly came out. Put the truck in neutral and the front output wiggled its way out. Now to swap in the locking output. I have found, if the output is in neutral or low, I can use the flange to slowly turn the diff and mesh the gears together. The it will push back. Doing this has sucked but, I will have a working CDL in about 1 more day.

Thanks a lot to therealassmikeg