Ok... found a pic not of my box but of the same one im using.



I did a little research on the saginaw steering boxes. It seems that there are 2 different size sector shafts, 1" and 1 1/8". And looking at the boxes, it looks like 63-82 corvette, 61-7? f100, and 65-68 mustang have the same basic box, just a different case for mounting. So it seems that i can use one of these, hopefully. Just need to find out the shaft diameter and find one that is the same.