Furnace age

I inspected a furnace today and could barely make out the data.
Model # 5838126302
Serial # 7209502
I think these are close to the best I could tell.
Could someone help me with the age?
Thank you

According to tech. ref. guide it is 1967

I could not find it in the Preston’s Guide 1965-2005. Which guide do you have or can you tell me where I missed it in Prestons. Thank you for you help!

It the Technical Reference Guide from CarsonDunlop. They say for furnace use serial number same as for air conditioners.

Thank you so much