I am not sure if RS has retrofit springs but in all likelyhood they will. I have seen other spring kits around shops that are relatively cheap but decent. I will go out on a limb to say that most posts I have yet worked on are virtually identical inside so far as the springs are concerned, so theres a chance RS would apply. The easiest solution is to take the post with you and see if it fits. Shops will usually let you trial fit if it doesnt scratch or anything.