Naw you can leave that sun assembled.
-There is a PLANETARY endplay spec, of .006 to .033.If this endplay is in spec, with those T-washers,you can reuse them. Just swap them around.They wear very,very slowly.That's why the spec is so generous. The spec has to be less than the height of the locating tangs tho, cuz if they spin, hmmm, if they spin, it's armageddon in there. heehee
-The DRIVETRAIN endplay also controls where those pesky cast rings ride and those rings direct the oil into the clutches and also where the pump oil goes.So the thrust washer in the center of the trans is supposed to push the entire front end forward to locate all those circuits.It's a generous spec of .030 to .089. That center washer is selective. There are three different thicknesses available.It is selective to compensate for wear in all the various front thrust washers, and for wear in the back bearing.So it's best to have a good back bearing.
BTW. those planetary T-washers can sometimes be installed wrong. They will fit into the planetary axles, and they will fit into the little rectangular cutouts provided for them. They only fit correctly to sit flat, in the cutouts.