Adding a stand alone tachometer

[GPG]

Good afternoon,

I would like to add a stand along auto meter tachometer to my Roxy but have not come across anything but the OBD2 feed to cell phone screen or similar. Does anyone have knowledge on this add on and if there is a signal that you can tie into? I see autometer has a marine tach that has a smaller rpm band which would be a bit easier to read at a glance.

Thanks
GPG