It was I who had the recent problem with the removal of the hub from the rear axle in order to get to a suspect seal. Sorry to report no further progress.  Phil

This rear bearing replacement is an evil job.

It is wise to understand the general layout of the task and I have provided a small section of a similar (not identical) configuration as a reference point. It is always wiser to understand what is happening.

One must also consider all risks at all stages and take the greatest of care. Where will the impacts be going...(every action has a reaction!), where are your fingers, what parts can be damaged (aside from
yourself)...etc etc.  At the moment, the only fully functioning spare Plus 8 Salisbury 7HA I know of on the planet, is my old one. (sad smile)

You will need a new Timkin bearing (or 2 for both sides) and two oils seals per side....and inner one and the outer one.

To access the wheel bearing (41) one must remove the axle shaft (45). To remove the axle shaft you must be able to exert some force on it as it will be pretty tightly on.

You remove the drum, the brake shoes, brake cylinder and bolts from the backing plate as these bolts hold the bearing cap. You need the driving plate (hub), as this is will be the base to attach your pulling device or accept the blows necessary to remove the assembly.

Now go rent a slide hammer....a large one with a heavy weight. This is a cute tool with a long round shaft on which a hammer weight slides. The impact produced by quickly moving the weight towards the end of the shaft is used for pulling out the driving flange, the half shaft, etc.. You will need a slide hammer that can be used with the driving flange you have...often these can be rented with different fittings. After many whacks and much patience, the whole assembly should detach from the differential and there will be your bearing..likely still attached to the shaft. Not to worry, the fun may be just beginning! PLEASE note
where everything piece goes and its alignment. You must be very careful as there are four shims there that require careful placement to eliminate end play.

It may also be possible to remove the assemble if you can whack the hub from the rear ...(ugh)

Properly functioning bearings decrease friction and therefore reduce heat. Improperly functioning bearings will not do so and the heat therefore produced can actually weld the bearing to the shaft. Sometimes
this can be removed with careful whacks and sometimes you can cut mostly through the bearing (DO NOT TOUCH THE SHAFT!) and then remove the weakened remainder. No diagnosis or prognosis can be made until you are there.

You must also ask yourselves why this happened. Most will never have to change their rear bearings. The bearing could have been defective (unlikely), the installation was improperly done, the seals failed or
the axle was not greased...the greasing actually packs the bearing with grease.

Axle Shims -3HA Salisbury
Gerry Willburn at the eMog Pub

The 3HA Salisbury axle in your 1955 Plus 4 is a semi-floating type. The shims are, as you guessed, to control the end play of  the axle. This should be between 0.001 to 0.005 inches (0.025 to 0.125 mm). The bearings are NOT pre-loaded.

You have to re-assemble the axle with the shims in order to measure the end play. You also want approximately the same thickness of shims on both sides of the axle.

Assuming that it was nearly correct to begin with, re-assemble the axle with as close to the same thickness of shims on both ends as you can. Using a piece of hardwood to protect the threads on the axle ends, bash on the end of the axle from both sides of the car to seat the shims and outer bearings.

Mount a dial indicator to the backing plate and measure the end  play of the axle as pressure is asserted on both ends, Then  adjust shims as required to achieve the required 0.001 to 0.005  inch play.
It sounds harder than it is. Gerry

Additional comment as to WHY they are needed:

The cumulative tolerance of the axle shaft lengths and the thrust button shaft in the diff with respect to the total length of the axle housing needs to be accounted for.

Also, during use, the end faces of the thrust button shaft and the ends of the two axle shaft wear against each other so the axle end-play increases. Eventually the thrust button would have to be replaced.
Mike Miles