Since I've been doing this fairly recently...

In addition to Tom's advice, if you current syncro doesn't have the
locker, then you'll want to run the vacuum lines up to the front (so
you will be able to use the locker once it is in). It's a lot easier
to get them routed with the transmission out. The electrical line for
the indicator lamp should already be back there. In the case of a
syncro without a locker I'm not sure where they might tie it up. The
decoupler wiring harness gets left in the driver side (left) rear
wheel well. You might find the other wiring there too.

The engine doesn't have to come out. And, IMHO, it is a lot easier if
you don't have to pull the engine. Make sure you have at least 2 jack
stands. Putting the vehicle up on 4 isn't a bad idea. Put them up as
high as you can.

A real transmission jack can be useful, but a regular floor jack will
do the trick.

Get a helper. You'll appreciate him.

Get lots of brake cleaner. Use it on the CV joint bolts BEFORE you do
anything. Get them really clean. It will make them come out real easily.

Get Super Penetrant, or equivalent. If either van has been sitting
around for a while, this stuff will make getting off those old nuts
and bolts MUCH easier.

When putting things back on....clean, clean, clean. Nuts and bolts go
on a lot more easily if they are clean. I used a blast cabinet to
clean up mine, and then used a spray on (cold) galvanize spray to
help prevent rusting down the road.