Age of Red T Coil Furnace

I inspected a condo yesterday and it had a Red T Coil furnace. Model number RTVX-316-30.8KW and Ser # 2180892. The unit was built in 1991 according to the property appraiser’s web site. I think the furnace is original but would like to confirm it. Anyone know how to determine that from the serial number on these units?

looks like 92 to me.

That serial shows Aug 1992…