I know this is a very old thread, but here's what I did for two Phillips drivers. The first driver was one I got from ebay because I wanted an extra to keep in the car and wanted the handles to match my set. I also bought two new Snap On Phillips blades from ebay.
I used a 21mm socket to tap...
I've gotten a lot of good info here, so I thought I'd join in. I'm a retired school teacher but worked many years as a service station and dealership mechanic. I still have the majority of my Snap On tools that I started buying in the late '60s.
I'm still a car nut; I currently have an '09...