Oowee Tabernacle de Calis de Ice Teee my Young Quebecer de Caou! That hurts Man! But I agree with Greg and Frog. My 2 cents is Thats not suppossed to happen up front in 2WD. Looks like some wild spinning on ice/hit dry pavement abuse in 4wd to break teeth off the front like that. IMO the u-joints in the 1/2 shaft should break first or the axle end splines shave downlike a carrot before that happens.
As for the rear that looks like plain bad luck/abuse to me! I have 236,000 Km of controlled abuse on mine and all is still there! Maybe its Time to upgrade to a 2500 HD.
Just happens, My Truck is in for new Gears and Auburn next week! I got 3.55's coming outta mine, perhaps I should keep them and sell em to you as I don't think you can buy the small piece in the rear but your lookin at Crown and Piniion in the front (picks).
But you have 20" Wheels so to me my Gears would be useless to you! That could be alot of labour to disassemble! If you gotta pay labour, then like Daniel said may as well get a gear uprade and an Auburn (for street) or DTT (serious offroad or Track abuse) while your at it.
Unfortunately your lookin at 2700 to 3100 Bucks Bill CAD for a reputable shop to do it with Warranty. Otherwise option is to get two diffs from a wrecker, which run about 800 for the front C205 and 1200 for a basic rear one wheel wonder or if your luckey enough to know someone who works on these diffs maybe won't have to pay $99.00 an hour.
Best of luck and keep us posted.