F350 4x4 PSD rear diff questions??? (posi)

[spoolinturbo]

First off ill start with i have a 1996 ford F350 4x4 powerstroke. What kind of rear diff does it have? I see people that say dana 70 and 10.25. What kinda of rear is it? Is it a dana 70 10.25? (cause i know when i did the rear in my trans am i had to get the gears for the right 10 bolt, there was 7.5, 8.2 etc)
So my question is what kind of diff is it and what kind of options do i have to make it lock posi? I put my chip in and im tired of not being able to move in the rain now lol. I wanna know my cheapest option. Posi, Locker? etc Where can i get one? Best place with cheapest prices? Want anyones opinions on what will be the best way to go

Thanks in advance

[Gruss]

It's a Sterling 10 1/4" Factory you could get an open or a limited slip, not sure what is available in the aftermarket.

[Fordman247365]

look up your axle code, it will tell you what the gearing is and if it is a limited slip, ex. if it has a letter first... C9 or H33 ...not just a number it is a limited slip. code is on your door tag