when I did mine,I asked Moser about it

they said the 489 with the block in would be ok to run it...

I ran it 8 yrs or so and never a problem out of it,daily driving aleast 90 miles a day

I swaped to a 742 open and took a cold chiesle to the block and broke it in 3 piece and removed it

ran about a yr or so,then had a green bearing go out and start leaking oil

replaced the greens and run it with out the axle tube seals this go round as well...

o-ring on the bearing seals the tube up

so.IMHO..either way will work and end seals are not needed either

but the axle seals are a double protection on the ends against leaking

you have to remove the carrier and ring gear to remove the cross pin IIRC

some do ...some dont...up to you