How do you get a Suspension to hook, when the track surface is marginal at best

Did a pre assembled of my axle housing today to get the pinion angle, and center the axle in the car. So the leaf spring purch can get welded to the housing.
cleaning up the nut for the "axle to housing" and notice some think i have not noticed before. the nuts on the right side were normal but the ones on the left side had a tiny hole drilled in the nuts with plastic injected into them.

Not that it matter, just something i have never noticed before.
nuts 2.PNG axle nuts.PNG