I am replacing old Ground Control springs that were installed by previous owner with Eibach Pro-kit. Ground Controls have smaller diameter, so I can't reuse old upper spring seats.

On the rear the springs perfectly fit on the mounting rubber. So I installed them without upper spring seats (I didn't realize that I was missing the seats until I got to work on front .) What could be the consequences of that? Is it likely that the mounting rubber wears out under spring pressure, and the springs break the body?

On the front I have no choice but to get OEM seats and bearings. Do I need the bound stopper and upper/lower seat rubbers?