Yep. Thats where it used to be. Looks like the PO used that for the gauge. No wonder the thing is so hard to start. Are you sure the glow plugs are working? On the older system, this switch also disabled the glow plugs when the engine was warm (why I'm not sure).
Too bad because theres a corresponding port on the drivers head up front he could have used for the gauge. Perhaps the mercury tube wasn't long enough that came with the gauge (Princess auto strikes again :D).
If you want, give me a call or PM me and I'll help you wire in the correct switch and convert the glows to the new system. Want to see this thing anyways.
Billl