axel bumpers

what is the best way to install shock bumpers on a 67 chevelle rear axel ?

Do you mean the Jounce Bumpers? Small rubber pads near each end of the axle tube, that cushion things if the suspension gets bottomed out?
If so, they usually have a stud molded in them, with a nut to retain it in place on the tab welded to the axle tube. Here is a picture of a '67 axle tube for reference. The jounce bumper is the wedge-shaped rubber piece between the brake backing plate and the coil spring perch.
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