Great thanks for that info, only one more code needed. I still need the code for the base 6 cyl convertible spring 3917541. You are correct on the Sprint convert using the same spring as a 400 convertible. The spring usage chart shows the 3917545 used on sprint convertible, base 6 cyl convertible when ordered with firm ride & handling, 326HO convert, 400 convert, and any V-8 convert when ordered with firm ride and handling.