You can change the hanger lower mount either way.
If you remove the wedge lock bolt, you can push the pivot pin back without removing it from the axle casing enough to change the mount.
Careful with the wedge, they are very brittle.........
The other way, [ which I do if doing a pinion seal at the same time],
you will have to take the pinion nut off to remove the flange.
The trick here is to index this nut in relation to the pinion shaft
for re-assemby, as you do not want to overtighten the crush bushing
any further than spec torque. This will get you back to where you started , which is a safe way to do it.
However , I prefer to set the torque preload on the pinion to Spec. , so i use the inch lb conversion of 24-26 in/lb to set the crush load.
The reason this is a better way is that by indexing, you are only assuming the preload was correct before you removed the nut , whereas I find that most used units have some bearing wear and can use a little more load to come back to factory specs. This can only be done with touque readings and is a tricky little job [ until you have done one]
Most I have done usually wind up requiring about a 1/16th to 1/8'
more turn, but do not use that info without taking torque readings and doing it the correct way.
If you go the flange removal route, index the flange also and change the seal while you are there , for sure.
Most hanger mounts deterioration is caused by a long time leaking/seeping pinion seal, anyway. [ aside from the inferior design of the early 2 piece ones]
A word of caution:
If you over -tightened the pinion nut and cause the crush bushing to be to tight, you can NOT loosen the pinion nut for correction... the crush , once crushed, will not return by loosening the pinion nut and MUST be replaced if this happens, so use care...
Also remember, the torque of the pinion nut is a very high torque , whereas the torge spec for the bearing load measure is very low, so do not confuse the two.
The load spec I talk of [ 24/26 in/lbs]is the force required to turn the pinion shaft with no load on the differential [ brakes,etc], whereas, the pinion nut torque is the actual tightening torque of the pinion nut with the flange locked.. [ pry bar ].. and the torque
on that nut determines the load on the crush/bearings, so it is not a specific torque, but rather, what ever it takes to get the load spec correct..
A little long winded on this subject, but another important item to consider with the new hanger installed ... it is best to position the hanger before hanging the rear end. the important setting is to have the hanger at 90 degres in relation to the left/rear axle [ the fixed axle].. it is best to use the center line of the axle casing rather than the axle casing itself, as they have a slight taper.
Other measures are lateral, but thay can be close enough by measuring the old one before removal. Once therse are established , you can tighten the cinch bolt.
The last measure is axle centering after the whole axle has been installed . This is done with the cross link/strut adjuster nuts and I have a pictoral somewhere here on the site explaining that and a diagram for an easy to make diyer tool...