Well. I understand that asking for clarification from you before providing advice seem to be irritating. Let me help you. "Spring perches" or "mounts" might be considered different from say "Spring hangers" or even different than someone calling them frame mounts as opposed to axle mounts. So if I understand your question. Replacing your "Spring Hangers" at the rear of your vehicle and with all other factors remaining the same. You should have no issues. If someone made a previous change like say offset hangers then you might encounter a side load on your spring set requiring you to force them back in to alignment for reattachment. Something you might run into is if you need to replace the rubber within the eyelet. But since you didn't ask that question. I will avoid any hostilities and bow out here. Good luck.
Oh, don't forget. Safety first. Support the weight of the vehicle and not at the axle point.
