30566-01 is the part number for the entire kit and 30396-01 is the part number for the ACME screw itself.
We are migrating the naming convention so the first few days shipments will have the correct part number but names won’t be exact. We had to make a decision to hold orders and relabel the bags or ship them with some of the names accurate but not exact matches to the instructions. We decided that customers would be more upset if we held their orders to relabel all the bags since the part numbers were correct.