[Bob Carriere]

Hi Harry

You are on the coast and boats, particularly older ones being refitted have mechanical tachometer and each boat requires a different size cable drive.
I would shop around for boat restorers and the guy you find will be older than you.

I had a Chev T case driving a GMC speedo and the fittings of GMC and Chevy are not the same. Tracked down a retired instrument repair person who had retired but still did special orders, in particular for older boats, all his equipment were contained in one large spare bedroom. Walls were lined with cabinets containing odd spare parts. I was offered a choice of rubber encased waterproof casing or bare metal. Cost me less than a $100 BUT took me two hours to find his place in the country. Not sure if he is still alive but definitely not online.

See you on the docks.

Bob C