Strange upper serial numbers?

[Burns peter]

I have a 69 Globetrotter and I am wondering what the strange numbers above the serial number mean?

The name plate says the following:top to bottom

174 FJ
Land Yacht
A Travel Trailer
021T9S111

I understand the bottom serial number 021T9S111- Not International Trim, 21 feet long, twin bed, 1969, Santa Fe Springs, sequence #111

But does anyone know what 174 FJ means?

Thanks,

69Globe21 Peter