1994 Buick Century strut?

Try a different place.

Take it somewhere else for the alignment. They're correct that there should be a rubber insulator but it isn't serious if they're missing. There is a metal frame inside the rubber that rusts and crumbles away. There is not a real good way to tell until the springs are removed from the old struts. At that point the service adviser has to hunt you down and give you an updated estimate. First of all, most shops don't have those spacers in stock and don't want to put it back together until the parts come in a few days later. That means you would have to make a second trip back to the repair shop and the old struts would have been reassembled in need of an alignment. It's easier and faster to just install the new struts without those spacers.

Second, they often feel that you'll think as long as you keep agreeing to more parts, they'll keep coming back with more things they find later. They want very much to give you one estimate they can stick to.

Missing those spacers will cause the front of the car to sit about 1/2" lower than specified. Given the age, it will be sitting lower than normal anyhow due to the age of the springs. The car can still be aligned. Correct ride height is important for good tire wear even when the alignment is correct, but 1/2" on a front-wheel-drive car won't be noticeable.

I didn't mention that when I have done my own and the rubber was rotten/gone I used a piece of rubber heater hose slipped over first coil on spring to replace/simulate it.

Dandy idea. Wish I had thought of that. I assume it holds up to the weight of the car on the springs.

Hhmmm.I guess i'll have a look see tomorrow.