Age of Lennox Furnace

Can anyone help me with the age of this LENNOX furnace, the only number I could find was GH60-0.

Thanks in advance for your help!!

That looks like the model number. And the only thing that comes close to that number (in Prestons) was manufactured in the mid 60’s.

If you can locate the serial number, the first two digits are the plant number; the third and fourth digits are the year. The letter A is for January.

Beginning in 1974 the third and fourth digits of the serial number indicate the year followed by a letter indicating the month.

Note: the letter I is not used.

Thanks! David

The house was built in 1959, it looks original.

Thanks!!! Again