OK, the spacer is for the A-arm relocation,
see Hagen A-arm article, tho he didn't use
a spacer, he solved his with a different method.
You don't need it if you just switch to drivers
side CVs, and yes you want to switch to drivers
side CVs so you can change them easy on the
trail, 3 bolts instead of popping out the stubby
axle on the Pass side :-/
Be happy you got your spacer for free, I paid $60
to have one made, and what he said was not so
the axle won't pull out, it's so the CV won't pull
apart, and all the ball bearings fall out into the
dirt, kind of a pain on the trail

Use grade 8 nuts and bolts, lock washers and nylock
nuts, these darned things like to work loose, and
that's also a pain on the trail.
Wild