spent some productive time on it last night..
I was finally able to hold the top of the stud with a pair of plyers while turning the nut to get it loose.. used a bit of bush-mechanicry to squeeze the broken tail under the existing plate and nut to re-make the connection.
jumped it and got it started
did some more volt gauge test and found I was just not digging into the clamps enough with the probe to get a reading before, so it does nto matter where I put the probe I get a reading
but the dash gauge was still jumping randomly between both pegs while the handheld volt meter just jumped between 11 & 13
The jeep ran fine when I remove the positive terminal from the battery so I think the alt is still good, volt meter still wavered between 11 & 13 between the positive cable and the neg battery.
Let the jeep sit idling for about half an hour, shut it off and battery did not have enough to turn back over..