Do you drive this truck on the road?
If so, removing the spool in the rear axle will improve on-road behavior. The tire will not skid in a turn. However, your offroad traction will not be as good.
That said, you will need to remove the axles, then pull the third member to get at the differential itself and remove the spool. Try these links at Ack's FAQ (see link in signature, below) for removing the rear axles (found with a search for rear axle
Rear axle bearing install - Zukikrawlers
The above links will show you how to remove the axles - part of the third member removal process.
Once the axes are pulled out a few inches, you can unbolt and remove the third member (after draining the dif gear oil first!). If the third does not pop off easily, place a jack under the forward edge of the third member (NOT ON THE FLANGE!) and start raising the jack until the third pops loose.
Do a search at Ack's FAQ for dif
for a number of good illustrated tutorials on tearing down a differential. One actually describes how to install a spool.
Although longer shock may help, do not expect a giant improvement in your rig's ride! A crap ride is part of the deal when you own a Samurai - doubly-so if it is built.
I hope that this helps
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