1963 c10 rear end

[Fitzgerald63]

The spider gears recently went out in my 63 half ton truck rear end. The rear end is a factory GM 12 bolt from 1963 as far as i can tell. It has 3.73 gears and the 6 lug 17 spline axles.

My basic question is what guts from what years of trucks will fit in that year of housing? I have been told that they only made this style of rear from 63-65?

I am not opposed to switching everything to the 30 spline axle set up. I just don't know which ones if any will fit. I also plan on going posi as soon as i get the money, so which is easier to find posi for the 30 spline or the 17?

Any help or suggestions would be very appreciated. Thanks