Some of the earlier 822's could be expanded, IIRC, midland rewrote the CPU so that the out of band operation was eliminated on new ones. Some one correct me if I am wrong.
I had a 75-820 that I was able to expand, took some heating, scraping, and cleaning off of some sort of epoxy to get to the solder pads, BTW use your best pencil tip iron, the pads are tiny!!! I didn't see the need to keep it and sold it, I mostly rag chew on 38LSB. I then found a second 820 and again tried to get at the solder pads, but no luck. I stopped trying when I noticed when my iron started to discolor the PCB.
I too have the vehicle 12v plug/pl-259 connector and works just like a full sized rig, audio is typical tinny from the tiny speaker, but that's to be expected. Now I use it when I'm in the other 1/2's car, where she won't allow a permanently-mounted radio and it does pretty well. Wish I could find tuning and alignment info, there's a CB web shop that offers tuning/aligning/expanding, but his cost would be about what I paid for my 75-820 plus two-way shipping, for now I'm satisfied with it being stock. I use it as a loaner for non-cb friends when we take road trips, camping, and general farting around. **Jump_im**
73s
Greg