[BIG BLOCK JIMMY]

Thank you Sir! This is what the retailer states for the reason on the three shims:

"Kingpin GM, Dodge and Ford D60 front axles have a spring perch built into the differential side and because of that, if you put a shim under the front springs, the big u-bolt (Ford applications) or the studs (GM/Dodge) don't sit on the same plane as the u-bolt plate. To fix that, you can put a third shim on the top of the differential side spring pointing the opposite way, that makes sure everything sits square. For that reason, we offer our shims in sets of three."

I do have a 4" lift with 35" tires.

I will adjust the toe in myself now, thank you