Hankal wrote:

What's there to comment? It has to be in an IFR-approved installation
to be used for IFR.

It is an IFR installation.
Is a 337 required?
I am not an Avionics mechanic, so don't beat up on me.

But, you should be talking with one. Without an experienced Avionics
technician making the installation, it likely won't become an IFR
installation. The paperwork is a moving target, but is a lot easier today
than a few years ago. Whether it involves a 377 is academic becuase, if it
does, the competent shop will take care of that in course.