Are you sure the 300C has a vacuum pump pad? I know the 300D does.
Check the type certificate data sheets. Without a pad, this would be
really difficult--tho I have seen a belt drive setup on a C170. Make
it like
new 172s, with the same vacuum regulator, etc. Easier to STC.

As the other poster suggested, the in not a legal requirement to have a
pump.
I think an electric turn coordinator would be a great idea.

Bill Hale

gt wrote:
I would like to make my 1960 Cessna 172A IFR. Currently, I have only
venturi vacuum. My A & P stated that as there is no STC for a vacuum
pump intall, I need a form 337 field approval...I think it is form 337,
I could be wrong on that. Does anyone have information relating to
STC's and field approvals for vacuum pump installations on a
Continental 300-C?