ID this tachometer?

I just picked up this cool tach for the coupe. Anyone know what it is? There are no markings on it. It seems to be machined from solid aluminum and very well made. It's pretty heavy!

I will send it to Palo Alto Speedo to be overhauled to get it functional, but I'd like to know who made it/what it might be off of.

Any ideas?

Thanks in advance.

 

Looks like an old Pontiac? tach in a home brewed housing.

 

1965 olds Cutlass.

http://carsofgm.blogspot.com/2011/05/1965-oldsmobile-cutlass.html