First of all, a truck has a left side and a right side. It also has a front and a rear. It also has a top and bottom. So lets not get into "right side looking from the front" jazz. The right side is the passenger side and the left side is the driver's side

There is a code of AF for a 62-64 diff. It designates a 3.70 ratio. The rest could be a date with 2 as 62. This is all a guess. There are plenty of other numbers on that diff. They are covered up by paint, grime and some are stamped and some are cast. The stamped can be hard to see.

The question now is: What are we trying to figure out about this diff? What do you want to know and what are you going to do when you find out? You already know it's brake plumbing needs redone. You can figure the ratio. The era can be determined by visual comparison to other diffs and their covers. The shock mounts look correct from what I see. The helper springs were offered as a RPO. As said, it looks like a drop out, which is period correct (55-62). So what do you need? If you strip it down to find all the cast and stamped numbers you will then be able to research it down to detail. If you don't, you won't.

The 62 would have trailing arm rear suspension. Started in 1960. I don't see any signs of trailing arm brackets so probably a pre 1960 diff. Maybe even a 1958!!!!

The axle shaft is inside the axle tube. The markings are on the axle tube and possibly some in the webs of the dropout center section.

I agree that the riveted-on brake bracket looks original. But it was on the other side for 1958. So the only answer is it's some other chassis or a right hand drive frame or not a 1/2T or the guy had a giant rivet tool......or there is always the excuse: The Canadians did it.

I'm sure this is not a Ford 9"? What is the lug pattern? Does it have a rear cover on the diff?

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn