prop shaft removal

It’s time to replace the u-joints in my ’03 Sportsman 600’s front prop shaft. So, I soaked the front and rear splines with penetrating oil for a few days, then set about to remove the roll pin from the front yoke…..yeah, that ain’t happenin’! I’ve spent countless hours, and an entire can of penetrant……I’ve bludgeoned several pin-punches until they are un-recognizable, and virtually worn out a hefty ball-pein hammer. I guess my question is, "how much abuse can the front differential take?". I’m loath to use heat for fear of damaging the seal, bearing, etc…..but all that pounding can’t be good either. Drilling out a roll pin is difficult on the bench, using the drill press – I can’t imagine doing it on the bike! My instincts tell me to reach for a bigger hammer and pound away, but surely the front diff can’t survive?