Need help wiring a tach

[Kenfuzed]

Today I found this WICO tach at the Pomona swap meet and the seller had several gauges but this was the only one with a interface box (think that's what its called). Model number on the box says T-8 and it came with the Wico interface box. The tach is in beautiful condition but I can't figure out how it wires up.

The tach only has 2 terminals, one is marked + and the other is unmarked.

Then there is the interface box with 2 wires that came with it that has a white and black wire.

See pictures, I am trying to wire this to my HEI distributor.

[Kenfuzed]

Nobody???

I saw the original manual and instruction sheet on ebay but I'm not about to pay half the price of the tach for it. I know there has to be someone out there that has seen these before. Years ago I saw several installed in a few muscle cars but never thought to look at their wiring.

[Kenfuzed]

Forgot to add this...

It is tough to see in the photo but on the back of the box the left terminal with the black and red wire says "BAT -", the middle terminal with the brown wire says "P", and the right side terminal with the white wire says "BAT+". Going just on assumption it seems like the 2 existing wires would go to the posts on the tach, the BAT - and BAT + need leads from those obvious sources, and the P would have meant Points or the negative on the coil, thus the Tach output on a HEI distributor. This is purely assumption so I am asking in my desire not to blow up a very nice looking instrument. I've seen some schematics for other tachs requiring a filter, others without. Just adds to the speculation.

[Tazimafied]

Being a tach from the late 60's early 70's and going up to 8000 RPM I would assume this thing is for an outboard two stroke. Most similar automotive gauges from the same era that I have seen only show 5 or 6000 RPM. Mostly 5000. Hopefully someone else will chime in on this soon. You could also try some classic boating forums to see if they know what it is.

[Kenfuzed]

From what little I could find online the tach is for a V8 based on the "T-8" part number. Info suggests the tach also came in a 6 cylinder version called T-6. I also saw the same tach installed in a race truck back in the mid-80's.