You can about any older Pa plate but from what I understand you'll have to apply for a personal plate with the old plate's number. The state will send you a new issue plate plat you'll just put away. A buddy did that with his blue plate when they were being phased out. I have a yellow plate ready to go if I want to swap out my Pa Zoo plate.
That's nice to know. Never researched it, but just figured old plates were obsolete when the new design came out. I got a few blue ones, may look into down the road.