Keep in mind that while your Dana 35 shafts are unlikely to break with 33's, it really, REALLY, sucks when they do. If you don't have spare shafts with you, you will be screwed. Not to mention if it happens on a really tough trail it's going to affect everyone in the group in a negative way.
When the friend of mine broke her axle shaft, there were 4 of us wheeling that day, it prevented us from finishing the trail we were about 1/3 of the way on. We had to strap her wheel into place with a Hi-Lift stand so she could drive on it well enough to get back to camp. We all ended up turning around.
This is her Jeep after we got it ready to turn around to head back to camp...
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The moral to this story is if you're wheeling on something known to break that will prevent you from driving out on it, don't. Not saying your shafts will break with 33's but worrying about an axle shaft breakage only when it happens is the wrong time to worry about it.