I had to take mine completely apart to get out all the mud mixed with gear oil from the previous owner. It had formed a sticky mess that brake cleaner was not addressing. The spreader is not necessary, a careful prybar will get it out, and a couple hits with the deadblow hammer will get it back in, as long as you have everything squared up. I had removed the bearing caps from mine before removing the knuckles, and found that the severe beating I had to lay on knuckles to get them to separate had jarred the carrier loose. I found WD-40 was helpful in displacing water and mud that had gotten into the bearings.
If you are removing the axle seals, a long pvc pipe of the approximate inner tube diameter will make dislodging them easier. It will also ease alignment and prevent damaging the seals as you insert the shafts. I'd recommend leaving them alone unless they are leaking.
