I was looking at the shims in the upper control arm that are used to adjust the alignment and saw something interesting. Both sides have what looks like three shims there, front and back. The rear shims are covered with what looks like a glob of duct sealant. On both sides. This all looks original. So why did the factory cover the rear ones?
Most times, shims get re-used by alignment techs. I'm sure the car has had an alignment or two in 50 years
Sticking the shims together with an adhesive of some sort holds them in place as you tighten the nuts to secure them.
First pic is front shims. Second is rear shims. This is what I mean by a glob. Like this on both sides.
On some cars, it's difficult to get the shims to stay in place while doing the alignment. It's easier to tape or glue the shims together and install as one unit than to try to add or remove shims individually. I've done that many times.