I called autometer about a speedo gauge for my Ghia, they told me Mechanical, then they gave me another number to get the right cable, and that guy told me electric, and he sells the sender for $95 it only has 3 wires and the electric speedos are programable with 1 button. and the sender goes right on the end of the stock vw cable.
The problem is the gauge isn't made for our cars. they turn at differant RPMs.
sorry dude, as for getting it to work, the guy I talked to said he can build a gear box for it for $200? I think. but that won't last as long as the electric sender will. If you want I can find the number. I know it's not far. I still need to order my sender.
Hope it helps.