Slant Fin Boiler age please

Can anyone provide an age for a Slant Fin cast iron boiler:

Model M-120

Serial 12667

Thanks in advance.

Slant Fin has been inconsistent in their serial number coding, but based on the information I have, I’d actually make an educated guess and say that you have the seventh unit built in December 1966.

Most of the Slant Fins I find are at least 20 years old.

Slant Fin has no decipherable code. Give them a call at 516-484-2610 - press 2 for Tech Services.