When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The mechanically driven speedo still generates an electronic pulse ( 4 pulse I think ) this can be taken from the back of the clocks at the terminal marked RSW.I have an 96WRX and have just fitted a DEFI VSD11 Hud.
The terminal is next to the screw that holds the speedo to the pod (it is a screw though!) and is clearly marked RSW,in later cars the terminal is marked SP.