Air motor tachometer

[DesignerMike]

I am designing a unit with an adjustable speed air motor (Gast 4AM). I need a tachometer, only mechanical (no electric on the unit.

Gast doesn't make an add-on, but I have seen them on other units.
The tachs I have seen replaced the idle side bearing cover with the tachometer.

Any ideas where I could find an aftermarket part for these?

 

[MintJulep]

Google for mechanical tachometer returns 149,000 hits.

I bet one has just what you need.