Axle code on door sticker: C5 = 4.10 limited slip.

edit;
so that means you're looking for a front axle to match 4.10's (technically they're 4.09 gears up front.)
your front axle is called a D50 (dana/Spicer 50.)
however a D60 straight axle will bolt directly in its place (a common mod for off roaders/those with lifted trucks/plows,and those just with money to burn lol.)however the springs should be swapped as well,to those used with the D60.then you would need raise the rear axle 2" to match the increased lift of the front as well.this would essentially turn the truck into an "f350" with only the stickers door jam sticker differentiating it between the "f250".