Dropping things into the engine is bad times. I think its been discussed in many places that HFs and STD had 23 spline hubs and DX/Si had 26 spline hubs. As for the Distributor plug it has 7 on the HF/Si because they have CPS inside the distributor while its on the exhaust cam of a ZC. If you have a DX like I do the DX plug is the same as the one for the ZC so I just swapped that over.