A-Arms...Early vs. Late

[Hard Luck]

I know that the geometry changed in the SquareBodies and it may be that they changed a few times, and I heard that there may even be an improved turning radius on some of the trucks including the Suburban.

What I am wondering is where did the change happen? I have a 69 C10 but the 63-72's 1/2 tons would all be the same, on the 73-87's did they move the lower ball joint forward to provide more caster, or the upper ball joint back? Is the later upper pushed out for better camber?

The truck already has dropped disc brake spindles using the early (63-70) ball joints and I would be swapping the ball joints into what ever A-Arms I use. Looking to see if I can get better handling without spending $400-$700.

Thanks gang.