Tachometers and replacement

[Lake Superior charter ser]

I have a 1980 F- 30 Sedan and the lower station tachs are not working. Does anyone know the brand and where I can get them? Does anyone know how to remove the dash to get them out? What ever happened to Marine Tech? I sure miss there help. I believe the guy there was Larry and he retired. He had a wealth of knowledge and I wish I would have asked him these questions way back when. I sure would appreciate any help I could get on this Issue. Thanks Bill