I was wondering if anyone could tell me the advantages of a mini spool and the disadvantages of having it on a dd?

They are a low cost way to lock up - the mini
replaces the spider gears and locks the axle up.

Depending on the model of axle and the size of
the mini you can take the locking pin out of the
mini if you need to.

I see them alot over in the dunes - most jeepers
here in the desert go for a more expensive locker so that they can drive on the street.

Lockers like my ARBS cost 800-900 plus install
and require an air compressor, lines, switches , and MAINTENANCE. If you can find a Mini for your axle it might only cost $120 compared with $1500 for a single ARB setup.

All the spools that I see are on quasi race vehicles - trailer queens - every one - so you
loose road-ability ...