Mike when you say Disc are you referring to the rotoflex conversion kit which replaces the rubber flex coupler? Either way I dont suspect replacing the couple would be any problem. The problem right now is the studs on the drum turning and making it immpossible to remove the nuts and the shaft. Cant service the shaft or replace the coupler until the shaft is removed.

 

also need to know if the rear nyclock nuts are the same size/grade as the nuts used for the front propshaft? Again a source claimed that the nuts for the front shaft are: 3/8x24 grade 5

 

Rear are the same, can't remember the length, but I can measure them if you need.
They are captive bolts like on the front output flange. To replace them you'll need a new nut for the output flange also.

 

Any nuts that hold a Ujoint flange to the TC or diff will be Nylock, 3/8-24.
You shouldn't really be reusing nylocks anyways. Do yourself a favor, jump on McMaster.com and order up a 20ct bag of the nuts, grade 8 or 5.

For the turning bolts, do as already mentioned. Take a torch to the nylocks and melt the plastic. That should help. Hit them with PB Blaster too.

 

You don't want to know what I did, but it will come to you if all else fails. My method required the replacement of the captive bolts.

 

He's got to replace those anyways since the heads are rounded. So let's hear it.

 

air powered cut off tool and a air powered grinder, lots of cussing, some beer, more cussing, some scotch, more cussing and success...

 

Ill try my luck once more, this time with a socket but if that does not work Ill use a dremel to saw off the bolts from the transfer case and replace with new. Question I have is what do these bolts/studs look like? I can only see the side that sticks out of the transfer case which connects the rear propshaft.

These:
http://img.diytrade.com/cdimg/330400...hread_rods.jpg

or these:
http://www-img.toolstation.com/image...bbig/34818.jpg

 

should be a standard bolt, not a stud...so #2

 

Lol he used the Blue Wrench....
Honestly I've never had one spin on me but I use an impact to remove them.
The land rover part # for the bolts is FRC3602 3/8x24x1 3/4"
The nyloc nuts NZ606041L
The 1/4" difference as was suggested earlier 1 1/2" may be the difference of the overall length.

The reason he is removing the driveshaft (which I suggested) is to check the park brake drum set screw.
I've seen this too many times (as many times as front driveshafts were replaced for the wrong reason) where the screw vibrates out then presses on the driveshaft flange causing a slight to severe driveline vibration . It's not always the case, but it's the right way to diagnose this issue based on the symptoms given, If it's loose and the vibration is fixed he's saved himself 300-400 for the time being. And the money saved can be spent on somthing else equally important(like a new brake booster)
If it's not fixed THEN a front driveshaft would be in order.
I'm only trying to help keep the priorities in order here.