Tim the two position switch you refer to from NAPA is 1/4" NPT

http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=MPEOP6620SB_0306379251

The 3 prong Jerry suggests is the way to go. If I am correct, with that switch, you can remove ground on pressure, or connect ground on pressure, or connect continuity on pressure. Good price too.


Deve

1950 Chevy 3100 Deluxe Cab
1950 Chevy 3100 Standard Cab
In the Stovebolt Gallery
The Think Tank
More info and tips at Deve's Technet