Need help identifying a Sun Tachometer

I picked up a Sun Electric Corp. tachometer recently from a friend and haven't found much about it on internet searches. It has the same style face as the football models but it does not have the red football on the face, rather it just has the words RPM x 1000. It is a 10K model, and the specs on the back are as follows;
model FZ-106 N
12V Negative ground
6 cylinder

The only connections on the back are, ignition, distributor and a ground. It may possibly be a marine tach, we found it in a pile with some boat pieces. It does not appear to need an external control box like some of the older Sun tachs.

Thanks

 

Probably from the mid to late '60s. Giveaway is that it doesn't require a sender, unlike the earlier ones right through the mid '60s that would just have a + and - on the back that would wire to the transmitter. What else do you wanna know?

 

Any idea of the value on this one? It is a little unusual in that it is a 6 cylinder model. The chrome is good and the dial face is not faded at all. It does not have a cup indicating that it was dash mounted, however it does have the bracket that holds it in place on the dash.