it's a 65mm socket, and yes it is very much needed, it's to undoo the main axle nut, which holds the disc and bearings onto the axle,
it's done up to about 650 newton meters, so you need a good strong breaker bar and a long scafold pole,
whats is wrong with your handbrake btw?? as they are small shoes inside the drum, they are not used for normal braking, so unless you have been doing lots of handbrake turns, they should never wear out,
if the van rolls a little when you have applied the handbrake, that's normal, tho if it's not gripping, could be oil on the linings, so you'll need oil seals replacing whilst the hub is off... wise to do that anyway as it's such a pain to get that big nut off.
Gazz, April 2010